JP2573429Y2 - Semiconductor heat treatment equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor heat treatment apparatus used for heat-treating a wafer for manufacturing a semiconductor.

[0002]

2. Description of the Related Art As a semiconductor heat treatment apparatus of this kind, a furnace body having an open lower end and a built-in heater, a quartz process tube disposed in the furnace body and having an open lower end and a closed upper end, There is a known one provided with a boat mounting table which can be moved up and down and which is positioned in a lower end opening of a process tube.

[0003]

However, in a conventional semiconductor heat treatment apparatus, when heat treatment is performed on a wafer, transfer of the wafer to a boat on a boat mounting table waiting at a lowered position is started, Until the mounting table is raised and the boat supporting the wafer is inserted into the process tube, a natural oxide film is formed on the wafer due to the influence of the heat in the process tube, and the electrical conductivity of the oxide film formed by the heat treatment is increased. There is a problem that the characteristics are deteriorated and the uniformity of the film thickness is impaired.

An object of the present invention is to provide a semiconductor heat treatment apparatus which solves the above problem.

[0005]

SUMMARY OF THE INVENTION A semiconductor heat treatment apparatus according to the present invention includes a furnace body having an open lower end and a built-in heater, and a quartz process tube disposed in the furnace body and having an open lower end and a closed upper end. And, in the raised position, located in the lower end opening of the process tube,
And a vertically movable boat mounting table on which a boat supporting the wafers is mounted. A closed chamber is provided continuously below the furnace body, and a nitrogen gas supply device and a heat exhaust duct are connected to the closed chamber. The supply device includes a control device that controls the amount of nitrogen gas supplied into the closed chamber to control the oxygen concentration in the closed chamber to an appropriate value, and a heat exhaust pipe having an electric damper is connected to the heat exhaust duct. Semiconductor heat treatment equipment
A nitrogen gas introduction chamber is provided outside the
The chamber and the nitrogen gas introduction chamber are communicated with each other,
Outside the bar, one end is connected to the closed chamber
And a nitrogen gas circulating duct connected at the other end to the nitrogen gas introduction chamber.
A nitrogen gas circulation duct is provided.
Circulation between the closed chamber and the nitrogen gas introduction chamber
Nitrogen gas circulation fan
Cooler to cool before returning to chamber, as well as circulating
Filter through which nitrogen gas passes before returning to the closed chamber
It is provided with .

[0006]

Before transferring wafers to a boat on a boat mounting table, nitrogen gas is supplied into a closed chamber by a nitrogen gas supply device, and the inside of the closed chamber is set to a nitrogen gas atmosphere. At this time, the control unit controls the oxygen concentration in the closed chamber to an appropriate value. In addition, by the electric damper of the heat exhaust pipe connected to the heat exhaust duct,
Prevents excessive oxygen from entering the closed chamber. In this state, the wafer is transferred to the boat, and then the boat mounting table is raised. Then, formation of a natural oxide film on the wafer due to the influence of heat in the process tube is prevented. Ma
In addition, heat-treat the wafer at least in the process tube.
Except when the boat is down,
Nitrogen gas when in a closed chamber.
Between the closed chamber and the nitrogen gas introduction chamber via the ring duct
When circulated, it is cooled by a cooler in a closed chamber.
Clean nitrogen gas flow through the filter
The wafers supported by the boat
Particles are prevented from adhering. In addition,
The raw gas is circulated and the oxygen concentration in the closed chamber is
Only when the value becomes higher than the positive value,
Since it is only necessary to replenish, it is possible to reduce the amount of nitrogen gas used.
it can.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the left and right of each drawing are referred to as left and right. Also, the upper side of FIG. 2 is referred to as a rear side, and the opposite side is referred to as a front side.

The semiconductor heat treatment apparatus comprises a vertical furnace body (1) containing a heater (2), and a vertical quartz process tube disposed in the furnace body (1) and having an open lower end and a closed upper end. (3) and a boat (5) on which a number of wafers (4) are supported at predetermined intervals up and down
Elevating boat mounting table for loading into
(6).

At the lower end of the process tube (3), when the boat mounting table (6) is in the lowered position,
A shutter (11) for closing the lower end opening of (3) is provided. At the lower end of the boat mounting table (6),
A lid (6a) having a larger diameter than the lower end opening of (3) is provided,
In the ascending position of the boat mounting table (6), the peripheral edge of the upper surface of the lid (6a) contacts the lower end of the peripheral wall of the process tube (3), whereby the inside of the process tube (3) is sealed.

[0010] A boat mounting table connected below the furnace body (1)
Closed chamber (15) for loading and unloading boats (5) to (6)
Is provided. A nitrogen gas introduction chamber (18) is provided on the right side of the closed chamber (15) via the right side wall (15a). An opening (19) is formed in the right side wall (15a), and a filter (20) is fitted into the opening (19). Nitrogen gas introduction room
A nitrogen gas supply device (16) is connected to the right side wall (18a) of (18) and communicates with the inside of the closed chamber (15) through the opening (19). The nitrogen gas supply device (16) adjusts the amount of nitrogen gas supplied into the closed chamber (15) and
A control device (1) that controls the oxygen concentration in the
7).

Outside the closed chamber (15), one end is connected to the lower end of the left side wall (15b) of the closed chamber (15), and the other end is connected to the right side wall (18) of the nitrogen gas introduction chamber (18). A nitrogen gas circulation duct (21) is provided at the lower end of 18a). A cooler (22) is provided at an end of the nitrogen gas circulation duct (21) on the side of the nitrogen gas introduction chamber (18). Further, a nitrogen gas circulation fan (23) is arranged at a lower end portion in the nitrogen gas introduction chamber (18). Therefore, the nitrogen gas introduced from the nitrogen gas supply device (16) into the introduction chamber (18) passes through the filter (20), and after the remnants are removed, enters the closed chamber (15) and the fan (23) ), Is sucked into the circulation duct (21), cooled by the cooler (22), and then reenters the introduction chamber (18). Thus, circulation is performed between the closed chamber (15) and the nitrogen gas introduction chamber (18).

A heat exhaust duct (7) is connected to the upper end of the right side wall (15a) of the closed chamber (15). Duct (7)
Is connected to a thermal exhaust pipe (10) having an electric damper (8) and a displacement adjusting damper (9). The closed chamber (15) is provided with a maintenance door (not shown), such as a keyed sealing door or an electromagnetic lock in order to prevent accidents caused by lack of oxygen. It is better to use a ceiling door with a seal.

A cassette waiting room is provided behind the closed chamber (15).
(25) is provided. Waiting room (25) and sealed chamber (15)
An isolation door (26) is provided therebetween. Waiting room (25)
Inside, a plurality of cassettes (28) supporting a large number of wafers (4) are removably mounted on a rotatable cassette support device (27).

In such a configuration, when performing a heat treatment on the wafer (4), a predetermined amount of nitrogen gas is first supplied into the closed chamber (15) by the nitrogen gas supply device (16) to form a nitrogen gas atmosphere. Then, the oxygen concentration in the chamber (15) is set to an appropriate value by the control device (17). Also, heat exhaust duct
The electric damper (8) of the heat exhaust pipe (10) connected to (7) prevents excessive oxygen from entering the closed chamber (15), which also reduces the oxygen concentration in the chamber (15). Set to an appropriate value. In this state, the isolation door (26) is opened, and the wafer (4) is transferred from the cassette (28) to the boat resting on the boat mounting table (6) by the transfer device (not shown).
Transfer to (5). Next, the boat mounting table (6) on which the boat (5) supporting a large number of wafers (4) is mounted is lifted by a lifting device (not shown), and the boat (5) and the wafer (4) are completely processed. Put the tube into the central heat equalizing section of the tube (3) and bring the lid (6a) into contact with the lower edge of the peripheral wall of the process tube (3).
The lower end opening of (3) is completely closed by the lid (6a). The lifting speed of the boat mounting table (6) should be such that thermal distortion does not occur on the wafer (4). In this state, the process tube
The wafer (4) in (3) is subjected to a heat treatment to form an oxide film. During the heat treatment, the inside of the closed chamber (15) is kept in a nitrogen gas atmosphere.

When the heat treatment is completed, the boat mounting table (6) is lowered. The lowering speed of the boat table (6)
(4) Set the speed so that thermal distortion does not occur. At this time, since the inside of the closed chamber (15) is kept in a nitrogen gas atmosphere, formation of a natural oxide film on the wafer (4) is prevented. Thereafter, the isolation door (26) is opened, and the wafer (4) subjected to the heat treatment is transferred from the boat (5) to the cassette (2) supported by the support device (27) of the standby chamber (25) by the transfer device.
Transfer to 8). Then, the unprocessed wafer (4) is transferred to the boat (5) on the boat mounting table (6), and heat treatment is performed in the same manner as described above.

At least the boat (5) and the boat
Wafer (4) supported by the process tube (3)
The wafer (4) is heat treated
When the boat is removed, that is, when the boat (5)
When the gas is in the chamber (15), the nitrogen gas
After (21), the closed chamber (15) and the nitrogen gas introduction chamber (18)
When circulating between the cooler (22) in the closed chamber (15)
Clean nitrogen cooled by air and passed through filter (20)
A gas flow is created which is supported by the boat (5)
Particles may adhere to the wafer (4)
Is prevented. Therefore, contamination of the wafer (4) is prevented.
You. After the heat treatment, before lowering the boat (5)
Then, as described above, the nitrogen gas is
After (21), the closed chamber (15) and the nitrogen gas introduction chamber (18)
It is preferable to circulate between them.

In the above, when the boat mounting table (6) is lowered, the high-temperature processing gas and the excess nitrogen gas in the process tube (3) are supplied to the thermal exhaust pipe (7) connected to the thermal exhaust duct (7). Exhausted through 10).

In the above embodiment, the nitrogen gas supply device is connected to the closed chamber (15) via the nitrogen gas introduction chamber (18), but the present invention is not limited to this. It may be directly connected.

[0019]

According to the semiconductor heat treatment apparatus of the present invention,
As described above, it is possible to prevent a natural oxide film from being formed on the wafer before the heat treatment. Therefore,
The electrical characteristics of the oxide film formed on the wafer by the heat treatment are improved, and the film thickness becomes uniform. Also, the wafer
Prevents fine particles from adhering, and as a result
Wafer contamination is prevented. In addition, the amount of nitrogen gas used
And reduce costs.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a semiconductor heat treatment apparatus of the present invention.

FIG. 2 is a horizontal sectional view of the same.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Furnace body 2 Heater 3 Quartz process tube 4 Wafer 5 Boat 6 Boat mounting table 7 Heat exhaust duct 8 Electric damper 10 Heat exhaust pipe 15 Closed chamber 16 Nitrogen gas supply device 17 Control device 18 Nitrogen gas introduction chamber 20 Filter 21 Nitrogen gas Circulation duct 22 Cooler 23 Nitrogen gas circulation fan

Claims (1)

(57) [Scope of request for utility model registration] 1. A furnace body having an open lower end and a built-in heater, a quartz process tube disposed in the furnace body and having an open lower end and a closed upper end, and a lower end opening of the process tube at a raised position. Located,
And a vertically movable boat mounting table on which a boat supporting the wafers is mounted. A closed chamber is provided continuously below the furnace body, and a nitrogen gas supply device and a heat exhaust duct are connected to the closed chamber. The supply device includes a control device that controls the amount of nitrogen gas supplied into the closed chamber to control the oxygen concentration in the closed chamber to an appropriate value, and a heat exhaust pipe having an electric damper is connected to the heat exhaust duct. Semiconductor heat treatment apparatus, wherein a nitrogen gas introduction chamber is provided outside the closed chamber.
In addition, the closed chamber and the nitrogen gas introduction chamber are communicated,
Outside the closed chamber, one end is connected to the closed chamber
While the other end is connected to a nitrogen gas introduction chamber.
A circulation duct is provided to circulate nitrogen gas.
Between the closed chamber and the nitrogen gas introduction chamber via the ring duct
Circulating nitrogen gas circulation fan, circulating nitrogen gas
Cooler before returning to the closed chamber,
Ringing nitrogen gas passes before returning to closed chamber
A semiconductor heat treatment apparatus including a filter .