JPH0640545B2 - Wafer heat treatment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a heat treatment method for a wafer in which an oxide film or the like is formed on the wafer surface.

(Prior Art) A heat treatment method for a wafer in which an oxide film or the like is formed on the surface of a wafer or the like constituting a semiconductor device is conventionally performed by a method shown in FIG. 4, for example.

That is, in the figure, reference numeral 1 indicates a heat treatment furnace formed in a tube shape, having one or a plurality of gas inlets 2 at one end and an opening 3 at the other end, and a plurality of wafers 4 is formed by one or a plurality of wafers. It is placed on a holding table (shell boat) 7 arranged in a transfer tube 6 having a gas inlet 5.

Then, for example, when forming an oxide film on the wafer 4, first, an inert gas such as nitrogen gas is introduced from the gas inlet 2 and the gas inlet 5 to inactivate the inside of the heat treatment furnace 1 and the transfer tube 6. A gas atmosphere is used (a).

After that, the wafer 4 together with the transfer tube 6 is inserted into the heat treatment furnace 1 through the opening 3, oxygen gas is introduced through the gas introduction port 2 and the gas introduction port 5, and the inside of the heat treatment furnace 1 and the conveyance tube 6 are introduced. Impurities such as nitrogen gas are removed (b).

Next, oxygen gas and hydrogen gas or oxygen gas are introduced into the gas inlet 2
The heat treatment furnace 1 and the transfer tube 6 are heated to a mixed gas containing oxygen gas or an oxygen gas atmosphere, and heat treatment is performed for a predetermined time according to a desired film thickness to form an oxide film. At this time, the gas from the gas inlet 5 is shut off (c).

After that, an inert gas such as nitrogen gas is introduced from the gas introduction port 2 and the gas introduction port 5 to create an inert gas atmosphere in the heat treatment furnace 1 and the transfer tube 6 (d).

After that, the transfer tube 6 and the wafer 4 are taken out from the heat treatment furnace 1 (e).

(Problems to be Solved by the Invention) However, in the conventional wafer heat treatment method described above, since a large number of wafers are processed at the same time, the distance between the wafers is close to, for example, about 3/16 inch. In the meantime, when introduced into the heat treatment furnace, an inert gas such as nitrogen gas filled in the transfer tube may remain during this period. For this reason, there is a problem that a uniform heat treatment cannot be performed because, for example, an oxygen gas or a mixed gas atmosphere containing an oxygen gas does not exist around the wafer and an oxide film is not uniformly formed. Further, in order to avoid such a problem, a step of introducing oxygen gas to remove impurities needs to be performed for a long time, which causes a problem that productivity is deteriorated.

The present invention has been made in view of such conventional circumstances, and an object thereof is to provide a wafer heat treatment method capable of performing uniform heat treatment and improving productivity.

[Structure of the Invention] (Means for Solving Problems) That is, according to the method of the present invention, a wafer is housed in a transfer tube, and the transfer tube is inserted into a heat treatment furnace to supply oxygen gas or oxygen gas. In the wafer heat treatment method of performing the heat treatment of the wafer in a mixed gas atmosphere containing the wafer, the wafer is inserted into the heat treatment furnace in a state where a gas containing at least oxygen gas flows into the transfer tube accommodating the wafer.

(Operation) According to the wafer heat treatment method of the present invention, when the wafer is inserted into the heat treatment furnace together with the transfer tube and the heat treatment is started, an oxygen gas atmosphere is already present in the transfer tube and the heat treatment furnace. However, since an impurity removing step using oxygen gas is not required and an inert gas such as nitrogen gas does not remain between these wafers, a uniform heat treatment can be performed efficiently.

(Example) Hereinafter, one example of the method of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows steps of a method according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a tube-shaped heat treatment having one or a plurality of gas inlets 2 at one end and an opening 3 at the other end. 1 shows a furnace, in which a plurality of wafers 4 are placed in a transfer tube 6 having one or a plurality of gas inlets 5 and are placed on a holding table 7 made of a material having high heat resistance and high cleanliness such as quartz. Placed on.

Then, for example, when forming an oxide film on the wafer 4, oxygen gas is first introduced from the gas inlet 2 to make the inside of the heat treatment furnace 1 an oxygen gas atmosphere. Further, a gas containing oxygen gas, for example, oxygen gas is introduced from the gas introduction port 5 to make the inside of the carrying tube 6 an oxygen gas atmosphere (ii). At this time, nitrogen (N ₂ ) gas may be mixed with oxygen gas.

After that, the wafer 4 together with the transfer tube 6 is inserted into the heat treatment furnace 1 through the opening 3, oxygen gas and hydrogen gas or oxygen gas is introduced through the gas inlet 2, and the heat treatment furnace 1 and the transfer tube 6 are oxygenated. In a mixed gas containing gas or an oxygen gas atmosphere, heat treatment is performed for a predetermined time according to a desired film thickness to form an oxide film. At this time, the gas from the gas inlet 5 is shut off. In an oxygen gas atmosphere, an oxide film is formed on the wafer even at room temperature. Therefore, in order to form an oxide film having a desired thickness, the residence time of the wafer in the heat treatment furnace 1, that is, the heat treatment time is It needs to be shorter than the conventional method (b).

Next, an inert gas such as nitrogen gas is introduced through the gas introduction port 2 and the gas introduction port 5 to make the inside of the heat treatment furnace and the inside of the transfer tube 6 an inert gas atmosphere (C).

Then, the transfer tube 6 and the wafer 4 are taken out from the heat treatment furnace 1 (d).

In the method of this embodiment described above, oxygen gas is introduced from the gas introduction port 2 and the gas introduction port 5 to create an oxygen gas atmosphere in the heat treatment furnace 1 and the transfer tube 6, and thereafter, together with the transfer tube 6, the wafer is transferred. Since 4 is inserted into the heat treatment furnace 1, the inside of the transfer tube 6 and the heat treatment furnace 1 are already in an oxygen gas atmosphere at the time when the heat treatment is started, and the impurity removal step using oxygen gas is not required. , Productivity can be improved. Further, since no inert gas such as nitrogen gas remains between the wafers, uniform heat treatment can be performed.

Further, in the method of this embodiment, when the heat treatment yields and the wafer 4 and the transfer tube 6 are taken out from the heat treatment furnace 1,
Although the inside of the transfer tube 6 and the inside of the heat treatment furnace 1 are set to an inert gas atmosphere such as nitrogen gas, for example, when performing heat treatment in an oxygen gas atmosphere, the inside of the transfer tube 6 and the inside of the heat treatment furnace 1 are oxygen gas atmosphere. The wafer 4 and the transfer tube 6 may be taken out as they are. In this case, in order to form an oxide film having a desired film thickness, it is necessary to further shorten the heat treatment time of the wafer 4 and the transfer tube 6 in the heat treatment furnace 1 as compared with the method of this embodiment. Further, argon gas or the like may be used as the inert gas, and O ₂ gas, O ₃ gas or a mixed gas thereof may be used as the oxygen gas.

In the apparatuses used in the methods of these examples, as shown in FIG. 2, for example, the gas discharge pipe 8 is provided at the end of the transfer tube 6, and the gas introduced into the transfer tube 6 and Gas and the like introduced between the transfer tube 6 and the tube-shaped heat treatment furnace 1 flow as shown by arrows in the figure and are discharged from the discharge pipe 8.

Further, in the methods of these examples, the horizontal heat treatment furnace in which the transport tube 6 is inserted into the heat treatment furnace 1 from the horizontal direction has been described, but the method of the present invention is not limited to such examples. For example, as shown in FIG. 3, a transfer tube 6a having a holding table 7a for holding a plurality of wafers 4a between a plurality of columnar bodies of three or more is arranged in a tube shape from below. Also in the vertical heat treatment furnace to be inserted into the furnace 1a, it can be carried out in the same manner as the above-mentioned embodiment, and the same effect can be obtained.

As described above, in the wafer heat treatment method of the present invention, uniform heat treatment can be performed without performing heat treatment with an inert gas such as nitrogen gas remaining between the wafers. It is possible to improve productivity without the need for a step of removing impurities by gas.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the steps of the method of one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing the main part of the apparatus shown in FIG.
FIG. 3 is an explanatory view showing a vertical heat treatment furnace, and FIG. 4 is an explanatory view showing steps of a conventional method. 1 ... Heat treatment furnace, 4 ... Wafer, 6 ... Transport tube.

Claims (1)

[Claims] 1. A wafer heat treatment method in which a wafer is housed in a transfer tube, the transfer tube is inserted into a heat treatment furnace, and the wafer is heat-treated in an atmosphere of oxygen gas or a mixed gas containing oxygen gas. 2. The method for heat treating a wafer according to claim 1, wherein the wafer is inserted into the heat treatment furnace in a state where a gas containing at least oxygen gas flows into the transfer tube accommodating the wafer.