JPH06151342A - Heating furnace for semiconductor manufacturing - Google Patents

Abstract

PURPOSE:To prevent moisture which has adhered to a semiconductor wafer and a boat from creeping into a furnace. CONSTITUTION:A nitrogen-gas nozzle 11 is arranged near a furnace port 3c in such a way that a gas spout 11 a is directed to semiconductor wafers 1 and a boat 2. Nitrogen gas which has been heated by a gas heating device 12 is supplied to the nitrogen-gas nozzle 11. Moisture which has adhered to the semiconductor wafers 1 and the boat 2 is heated by the heated nitrogen gas, and it is evaporated. Consequently, it is possible to prevent the moisture which has adhered to the semiconductor wafers 1 and the boat 2 from creeping into a furnace and to stop that the semiconductor wafers are oxidized inside the furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating furnace for semiconductor production, in which a semiconductor wafer is loaded and unloaded through a furnace opening while being supported by a boat.

[0002]

2. Description of the Related Art Conventionally, a heating furnace has been used for oxidizing a semiconductor wafer or forming a thin film in a semiconductor manufacturing process. Among heating furnaces of this kind, which are not particularly provided with a load lock mechanism, for example, doped polysilicon is used to form a direct contact electrode by CV.
When the film is formed by the D method, there is a problem that oxygen enters the furnace in the step of inserting the boat loaded with the semiconductor wafer into the furnace.

When oxygen enters the furnace, the contact resistance is increased because the doped polysilicon is deposited after the surface of the contact hole is oxidized. This becomes more significant as the contact hole becomes finer.

In order to prevent oxygen from entering the furnace,
Conventionally, the nitrogen gas was discharged from the heating furnace through the furnace opening, or the nitrogen gas was blown out near the furnace opening. Further, as disclosed in, for example, Japanese Patent Laid-Open No. 3-148113, a nitrogen gas nozzle for blowing nitrogen gas between semiconductor wafers loaded in a boat is provided in the vicinity of the furnace opening, and the nitrogen gas nozzle is used for the semiconductor wafer. In some cases, an exhaust port is provided on the opposite side to replace the air between semiconductor wafers with nitrogen gas. In addition,
In some cases, a nitrogen gas curtain was provided at the furnace opening to prevent oxygen entrapment. A conventional heating furnace of this type will be described with reference to FIG.

FIG. 2 is a sectional view showing a conventional heating furnace for semiconductor manufacturing. FIG. 2 (a) shows a state in which a semiconductor wafer is inserted into the furnace, and FIG. 2 (b) shows the semiconductor wafer in the furnace. The state where the inside of the furnace is evacuated after being inserted is shown. In these figures, 1 is a semiconductor wafer, 2 is a boat that supports the semiconductor wafer 1, and 3 is a heating furnace. The boat 2
Has a structure in which the semiconductor wafers 1 are kept horizontal and a large number of semiconductor wafers 1 are held at intervals between adjacent semiconductor wafers 1. Further, the boat 2 is structured to be lifted and lowered by a lifting device (not shown). That is, the semiconductor wafer 1 rises from the state shown in FIG. 2 (a) and is inserted into the heating furnace 3 as shown in FIG. 2 (b). After the predetermined heat treatment is completed, the semiconductor wafer 1 descends and goes out of the furnace. It will be.

The heating furnace 3 is formed into a bottomed cylinder by an outer cylinder 3a and an inner cylinder 3b, and a furnace port 3c for loading and unloading the semiconductor wafer 1 is opened in the lower part. Four
Is a nitrogen gas nozzle for supplying nitrogen gas to the space between the outer cylinder 3a and the inner cylinder 3b of the heating furnace 3, 5 is a nitrogen gas nozzle for blowing nitrogen gas to the opening of the furnace mouth 3c, and the nitrogen gas nozzle 5 is the furnace mouth. It is arranged concentrically around 3c. In addition, 3d is an exhaust port for exhausting the inside of the heating furnace 3, and is connected to a vacuum pump or the like (not shown).

Reference numeral 6 is a gas replacement nitrogen gas nozzle for replacing the air between the semiconductor wafers 1 with nitrogen gas. The nitrogen gas nozzle 6 is arranged in the vicinity of the furnace port 3c and is configured to blow nitrogen gas between the semiconductor wafers 1 loaded in the boat 2.

Reference numeral 7 denotes an exhaust duct for exhausting the air extruded from between the semiconductor wafers by the nitrogen gas blown out from the nitrogen gas nozzle 6 and the nitrogen gas near the furnace opening. The exhaust duct 7 is installed at a position facing the nitrogen gas nozzle 6.

In order to insert the semiconductor wafer 1 into the furnace in the conventional heating furnace 3 having the above-mentioned structure, as shown in FIG.
As shown in (a), the boat 2 is loaded with the semiconductor wafers 1 and then the boat 2 is raised at a low speed. At this time, nitrogen gas is blown from the nitrogen gas nozzles 4 and 5 and the gas replacement nitrogen gas nozzle 6.

When nitrogen gas is blown from the nitrogen gas nozzle 4, the inner cylinder 3 is inserted between the outer cylinder 3a and the inner cylinder 3b in the furnace.
A flow of nitrogen gas is generated through the inside of b toward the furnace port 3c. Further, when nitrogen gas is blown from the nitrogen gas nozzle 5, the opening of the furnace port 3c is filled with nitrogen gas. Therefore, it is possible to prevent outside air from entering the furnace through the furnace port 3c.

Although the air between the semiconductor wafers 1 cannot be sufficiently removed only by the nitrogen gas blown from the two nitrogen gas nozzles 4 and 5, this air is blown from the gas replacement nitrogen gas nozzle 6. The removed nitrogen gas is removed from the vicinity of the semiconductor wafer. That is, when the semiconductor wafer 1 moves upward into the furnace, the nitrogen gas blown from the nitrogen gas nozzle 6 is supplied between the semiconductor wafers 1 and the nitrogen gas containing air between the semiconductor wafers is supplied. Is exhausted from the exhaust duct 7 near the furnace opening.

In the conventional heating furnace 3, nitrogen gas was supplied to prevent air from being entrained in the furnace as described above.

After the semiconductor wafer 1 and the boat 2 are inserted into the heating furnace 3, the inside of the furnace is exhausted from the exhaust port 3d provided at the side of the heating furnace 3, and the heating furnace is heated by a heater (not shown). The whole 3 is heated to the set temperature.

[0014]

However, even if the structure for preventing the invasion of the outside air by the nitrogen gas is used as described above, there is an improvement in preventing the oxidation of the semiconductor wafer 1 in the furnace, but the sufficient effect is not obtained. I couldn't get it. this is,
Oxygen is introduced into the furnace only in the form of air such that it is held between the semiconductor wafers 1 and enters the furnace, or enters from the outside of the furnace into the furnace due to the diffusion phenomenon of gas. Instead, it is performed in the form of water attached to the semiconductor wafer 1 and the boat 2.

That is, since water cannot be removed by the conventional air intrusion prevention structure, when the boat 2 loaded with the semiconductor wafer 1 is inserted into the furnace and the heating furnace 3 is sealed, the semiconductor wafer is closed. The water adhering to 1 or the boat 2 remains in the furnace. In the case of a low-pressure CVD furnace, the air that has entered the furnace can be quickly removed by exhausting the inside of the furnace with a vacuum pump immediately after the boat 2 is inserted, but the removal of moisture adhering to the semiconductor wafer 1 and the boat 2 Takes a lot of time, and eventually the semiconductor wafer 1 is heated to a high temperature in a moist atmosphere and is oxidized.

The present invention has been made to solve such a problem, and an object of the present invention is to prevent moisture adhering to a semiconductor wafer or a boat from entering the heating furnace.

[0017]

According to a first aspect of the present invention, there is provided a heating furnace for semiconductor production, comprising a gas nozzle near a furnace opening for blowing heated inert gas supplied from a gas heating device to a semiconductor wafer and a boat. It is arranged.

The heating furnace for semiconductor production according to the second invention is
In the semiconductor manufacturing heating furnace according to the first aspect of the present invention, an ultraviolet light source for irradiating a semiconductor wafer and a boat with ultraviolet light is arranged in the vicinity of a furnace opening.

[0019]

According to the first aspect of the invention, the moisture adhering to the semiconductor wafer and the boat is warmed by the heated inert gas and evaporated.

According to the second aspect of the invention, the ultraviolet rays promote the evaporation of the moisture adhering to the semiconductor wafer and the boat.

[0021]

【Example】

Example 1. An embodiment of the present invention will be described below in detail with reference to FIG. FIG. 1 is a sectional view showing a semiconductor manufacturing heating furnace according to the present invention. FIG. 1 (a) shows a state in which a semiconductor wafer is inserted into the furnace, and FIG. 1 (b) shows a state in which the semiconductor wafer is inserted into the furnace. After that, the inside of the furnace is evacuated. In these figures, the same or equivalent members as those described in FIGS. 2A and 2B are designated by the same reference numerals and detailed description thereof will be omitted.

In FIG. 1, reference numeral 11 denotes a nitrogen gas nozzle for gas replacement as a gas nozzle according to the present invention. The nitrogen gas nozzle 11 is arranged in the vicinity of the furnace port 3c, and the gas ejection port 11a at the tip is the heating furnace 3. Semiconductor wafer 1 and boat 2 positioned at the insertion position when inserted into
Is directed to.

Reference numeral 12 is a gas heating device for heating the nitrogen gas supplied to the nitrogen gas nozzle 11. The gas heating device 12 is interposed between the nitrogen gas nozzle 11 and a nitrogen gas supply source (not shown), and heats the nitrogen gas sent from the nitrogen gas supply source to a predetermined temperature to the nitrogen gas nozzle 11. It is structured to supply.

Reference numeral 13 denotes an ultraviolet irradiation light source for irradiating ultraviolet rays. The ultraviolet irradiation light source 13 is arranged in the vicinity of the furnace opening 3c at a position substantially facing the nitrogen gas nozzle 11 for gas replacement, and at the insertion position. The semiconductor wafer 1 and the boat 2 which are positioned are irradiated with ultraviolet rays.

In order to insert the semiconductor wafer 1 into the furnace in the heating furnace 3 constructed as described above, first, referring to FIG.
As shown in (a), the boat 2 is loaded with the semiconductor wafers 1, and then the boat 2 is raised at a low speed. At this time, the nitrogen gas is blown from the nitrogen gas nozzles 4 and 5 and the nitrogen gas is blown from the gas replacement nitrogen gas nozzle 11 in the same manner as in the conventional case. Further, the ultraviolet irradiation light source is turned on to irradiate the semiconductor wafer 1 and the boat 2 with ultraviolet rays.

When nitrogen gas is blown from the nitrogen gas nozzles 4 and 5, a flow of nitrogen gas is generated in the furnace from between the outer cylinder 3a and the inner cylinder 3b through the inner cylinder 3b toward the furnace mouth 3c. The opening of the furnace opening 3c becomes filled with nitrogen gas. This reduces the air entrained in the furnace.

Further, when the nitrogen gas is blown out from the gas replacement gas nozzle 11, the gas heating device 12 heats the nitrogen gas. In this embodiment, the gas heating device 1
In 2, the nitrogen gas was heated to about 100 ° C to 200 ° C.

That is, the high temperature nitrogen gas heated to 100 ° C. to 200 ° C. is blown from the nitrogen gas nozzle 11 to the semiconductor wafer 1 and the boat 2. The air held between the semiconductor wafers 1 is pushed out of the vicinity of the semiconductor wafers 1 by this high-temperature nitrogen gas, and is discharged from the vicinity of the furnace opening through the exhaust duct 7. At the same time, the semiconductor wafer 1 and the boat 2 are heated by the high-temperature nitrogen gas, so that the moisture adhering to the surfaces thereof is evaporated. Note that this evaporated component is removed from the vicinity of the semiconductor wafer 1 and the boat 2 along with the flow of high-temperature nitrogen gas. At this time, if the semiconductor wafer 1 and the boat 2 are irradiated with ultraviolet rays, water is likely to be released from them.

In this way, the air between the semiconductor wafers 1 is replaced with nitrogen gas, and the semiconductor wafers 1 and the boat 2 are inserted into the heating furnace 3 while removing the moisture on the surfaces of the semiconductor wafers 1 and the boat 2. . After that, the exhaust port 3 provided on the side of the heating furnace 3 in the same manner as the conventional one.
The inside of the furnace is exhausted from d, and the entire heating furnace 3 is heated to a set temperature by a heater (not shown).

Therefore, the water adhering to the semiconductor wafer 1 and the boat 2 is warmed by the high temperature nitrogen gas sprayed from the nitrogen gas nozzle 11 and evaporated,
It is possible to prevent moisture from entering the heating furnace 3 in addition to air. Moreover, by irradiating the semiconductor wafer 1 and the boat 2 with ultraviolet rays, the moisture adhering to them easily evaporates, so that the intrusion of moisture can be reliably prevented.

When the exhaust duct 7 is arranged at a position facing the nitrogen gas nozzle 11 for gas replacement as shown in this embodiment, the flow of high-temperature nitrogen gas flowing in the vicinity of the semiconductor wafer 1, in other words, containing water. Since the flow of the high-temperature nitrogen gas is made uniform, the water content on the entire surface of the semiconductor wafer 1 can be removed in a short time. Even if the exhaust duct 7 is not attached, the effect of the present invention is not significantly impaired.

[0032]

As described above, the heating furnace for semiconductor production according to the first aspect of the present invention is a gas nozzle for blowing heated inert gas supplied from a gas heating device to a semiconductor wafer and a boat in the vicinity of the furnace opening. Due to the arrangement, the water adhering to the semiconductor wafer and the boat is heated by the heated inert gas and evaporated.

Therefore, it is possible to prevent the moisture adhering to the semiconductor wafer and the boat from entering the furnace.
The semiconductor wafer will not be oxidized in the furnace. Therefore, when the present invention is applied to an oxidation furnace, the film thickness uniformity of a thin oxide film is improved, and when the present invention is applied to a nitride film CVD furnace for capacitors, the capacity characteristics and the breakdown voltage are improved. Further, when the present invention is applied to the doped polysilicon CVD furnace, the contact resistance can be made as small as possible.

The heating furnace for semiconductor production according to the second invention is
In the heating furnace for semiconductor manufacturing according to the first aspect of the present invention, the ultraviolet light source for irradiating the semiconductor wafer and the boat with the ultraviolet light is arranged in the vicinity of the furnace opening. Therefore, it is possible to reliably prevent water from entering the furnace.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a semiconductor manufacturing heating furnace according to the present invention. FIG. 1 (a) shows a state in which a semiconductor wafer is inserted into the furnace, and FIG. 1 (b) shows the semiconductor wafer in the furnace. The state where the inside of the furnace is evacuated after being inserted is shown.

FIG. 2 is a cross-sectional view showing a conventional heating furnace for semiconductor manufacturing, FIG. 2 (a) shows a state in which a semiconductor wafer is inserted into the furnace, and FIG. 2 (b) shows a state in which the semiconductor wafer is inserted into the furnace. The state where the inside of the furnace is evacuated later is shown.

[Explanation of symbols]

 1 Semiconductor Wafer 2 Boat 3 Heating Furnace 3c Furnace Port 11 Nitrogen Gas Nozzle 12 Gas Heating Device 13 Ultraviolet Irradiation Light Source

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H01L 21/324 D 8617-4M (72) Inventor Mitsuhiro Tomikawa 4-chome, Mizuhara, Itami City, Hyogo Prefecture Mitsubishi Electric Co., Ltd. Kita Itami Works (72) Inventor Tetsuya Maekawa 4-1-1 Mizuhara, Itami City, Hyogo Prefecture Mitsubishi Electric Co., Ltd. Kita Ita Works (72) Inventor Nobuyuki Kosaka 8-1-1 Tsukaguchi Honcho, Amagasaki City, Hyogo Prefecture Sanryo Electric Co., Ltd.

Claims (2)

[Claims] 1. A heating furnace for manufacturing semiconductors, in which a semiconductor wafer is loaded and unloaded through a furnace opening while being supported by a boat, in the vicinity of the furnace opening, a gas heating device for heating an inert gas is communicated with the gas. A heating furnace for semiconductor production, comprising a gas nozzle for blowing an inert gas supplied from a heating device to a semiconductor wafer and a boat. 2. The heating furnace for manufacturing semiconductor according to claim 1, wherein an ultraviolet light source for irradiating the semiconductor wafer and the boat with ultraviolet light is arranged in the vicinity of the furnace opening.