JPH06260486A - Method and device for heat treatment - Google Patents

Abstract

PURPOSE:To eliminate the unevenness of temperature in the surface of a wafer when the wafer is heated and cooled at the time of heat-treating the wafer. CONSTITUTION:The front end of a wafer holder 16 is formed to mount a semiconductor wafer 18 and, at the same time, to place a heat buffer ring 20. Therefore, the wafer 18 is carried into a furnace tube 10 from the outside and heated to a prescribed high temperature from the ambient temperature with the ring 20 around the wafer 18. The wafer 18, in addition, is also taken out from the tube 10 and cooled to the ambient temperature from the high temperature with the ring 20 around the wafer 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment method and a heat treatment apparatus, and more particularly to a heat treatment method and a heat treatment apparatus for performing a high temperature short time heat treatment of a semiconductor wafer. In recent years, LSI
With the high integration and high speed of (large-scale integrated circuits), along with the ultrafine pattern forming technology, a shallow junction forming technology is increasingly required. In addition, this shallow junction formation technology uses high-temperature short-time heat treatment (RTA).
l) Establishment of technology is essential.

[0002]

2. Description of the Related Art A high temperature short time heat treatment using a conventional vertical type single wafer heat treatment apparatus will be described with reference to FIG. Heaters 32a, 32b, 32c for controlling the temperature in the core tube 30 are installed around the vertical core tube 30 made of a cylindrical quartz tube. Further, at the upper part of the core tube 30, there is an inlet 34 for supplying atmospheric gas. Further, a semiconductor wafer 38 is loaded in the tip portion of the wafer holder 36 made of quartz. The wafer holder 36 is moved up and down by a driving device (not shown) to move the wafer holder 3
6, the semiconductor wafer 38 loaded in
0, or it is carried out from the core tube 30 to the outside.

FIG. 6 shows an external wafer holder 36 and a semiconductor wafer 38, and FIG. 6 shows the wafer holder 36 and the semiconductor wafer 38 in a state of being loaded into the core tube 30, and the ascending and descending directions thereof are indicated by arrows. Further, although not shown, a wafer handling device for loading the semiconductor wafer 38 on the wafer holder 36 is installed at the end of the wafer transfer device installed between the front and rear processes.

Next, a high-temperature short-time heat treatment method performed by using this vertical type single-wafer heat treatment apparatus will be described. First, one semiconductor wafer 38 transferred by the wafer transfer device (not shown) from the previous step is loaded on the wafer holder 36 by the wafer handling device (not shown) (see in the figure).

Next, the wafer holder 36 is lifted by a driving device (not shown), and the semiconductor wafer 38 is
Are loaded into the core tube 30 from the outside (see in the figure).
At this time, inside the core tube 30, the heaters 32a, 32b, 3
Since the temperature is set to the predetermined high temperature by 2c, the semiconductor wafer 38 is heated from room temperature to the predetermined high temperature. Subsequently, heat treatment is performed at the predetermined high temperature for a short time.

Next, when the high temperature short time heat treatment is completed, the wafer holder 36 is lowered by the driving device,
The semiconductor wafer 38 is carried out from the inside of the furnace core tube 30 (see the figure). Then, the semiconductor wafer 38 is cooled from the high temperature in the core tube 30 to room temperature. Of course, when the semiconductor wafer 38 is loaded into the core tube 30 from the outside and unloaded from the core tube 30 to the outside, the wafer holder 36 is used.
Be careful not to apply heat stress to the semiconductor wafer 38 by controlling the ascending / descending speed of the wafer to avoid rapid heating and quenching.

[0007]

However, in the high-temperature short-time heat treatment method using the conventional vertical single-wafer heat treatment apparatus described above, even if the ascending / descending speed of the wafer holder 36 is controlled, the ascending / descending speed is too low. Then, as a result, the heat treatment is performed at a temperature of a predetermined high temperature or less for a considerable time, which deviates from the condition of the high temperature short time heat treatment, and the desired effect cannot be obtained. Therefore, the semiconductor wafer 3
8 when the semiconductor wafer 38 is carried in and out of the furnace core tube 30 by avoiding rapid heating and quenching and being careful not to apply thermal stress to the semiconductor wafer 38.
It is unavoidable that a temperature difference occurs in the plane.

That is, when the semiconductor wafer 38 is loaded into the core tube 30 and is unloaded from the core tube 30, the semiconductor wafer 38 is warmed from the peripheral portion and cooled from the peripheral portion, so that the surface of the semiconductor wafer 38 is covered. There is inevitably a non-uniform temperature between the peripheral part and the central part. For this reason,
During such heating and cooling, especially during cooling, temperature stress is applied due to temperature non-uniformity in the plane of the semiconductor wafer 38, resulting in the problem that wafer warpage and slip (crystal dislocation) occur. It was

In view of the above, the present invention provides a heat treatment method and a heat treatment apparatus capable of eliminating the non-uniformity of the temperature within the wafer surface during the heat treatment and cooling of the wafer and enabling a stable heat treatment. To aim.

[0010]

The temperature non-uniformity in the wafer surface during heating and cooling is "when heating an object from the outside to heat the object or when exposing the object to cool it to cool the object. It heats up and cools down from the surface and surroundings. ” That is, when the wafer is loaded into the high-temperature core tube from the outside, and when being carried out from the high-temperature core tube to the outside, the wafer is warmed from the peripheral portion and cooled from the peripheral portion, so that the peripheral portion in the wafer surface is The temperature nonuniformity occurs between the central part and the central part.

[0011] Therefore, the above problem is to install a thermal buffering on the outer periphery of the wafer when the wafer is loaded into the core tube from the outside and the wafer is heated from the external temperature to the high temperature in the core tube. After heating in a state, after performing a heat treatment on the wafer at a high temperature in the core tube for a predetermined time, the wafer is carried out from the core tube to the outside, the wafer from the high temperature in the core tube to the external temperature. This is accomplished by a heat treatment method characterized in that the wafer is cooled to a predetermined temperature while a thermal buffering is provided on the outer periphery of the wafer.

Further, after the wafer is loaded on the wafer holder, a thermal buffer ring is placed on the wafer holder so that the thermal buffer ring is located on the outer periphery of the wafer, and the wafer holder is driven. The wafer and the thermal buffering are loaded into the furnace core tube from the outside, and in a state where the thermal buffering ring is located on the outer periphery of the wafer, the wafer is heated from an external temperature to a high temperature in the furnace core tube, After performing a heat treatment on the wafer for a predetermined time at a high temperature in the core tube, drive the wafer holder, carry out the wafer and the thermal buffering from the inside of the core tube to the outside, to the outer periphery of the wafer. Cooling the wafer from a high temperature in the furnace tube to a predetermined temperature with the thermal buffering in place After the heat buffering was detached from the wafer holder, it is achieved by a heat treatment method characterized by taking out the wafer from the wafer holder.

Further, the above-mentioned problem is to provide a vertical core tube, a heater installed around the core tube to set a predetermined high temperature inside the core tube, a wafer holder, and a wafer holder for loading a wafer. Wafer handling means and a thermal buffering attachment / detachment for mounting the thermal buffering on the wafer holder so as to be located on the outer periphery of the wafer loaded in the wafer holder, or for detaching the thermal buffering from the wafer holder. Means and
Driving means for moving the wafer holder up and down, carrying the wafer loaded in the wafer holder and the thermal buffering located on the outer periphery of the wafer into the furnace core tube from the outside, or carrying out from the furnace core tube to the outside. It is achieved by a heat treatment apparatus characterized by having.

[0014]

In the present invention, when heating the wafer,
The thermal buffering is installed on the outer periphery of the wafer and functions as a thermal buffer between the heating medium and the wafer, thereby suppressing the temperature rise from the peripheral portion of the wafer. Therefore, it is possible to eliminate the temperature nonuniformity between the peripheral portion and the central portion within the wafer surface during heating.

Further, when the wafer is cooled, the thermal buffering is installed on the outer periphery of the wafer, and the thermal buffering temporarily functions as a heat insulating material, thereby suppressing the escape of heat from the peripheral portion of the wafer. . Therefore, it is possible to eliminate the temperature nonuniformity between the peripheral portion and the central portion within the wafer surface during cooling. Therefore, it is possible to suppress the occurrence of wafer warpage and slip due to thermal stress during heating and cooling of the wafer, and to realize stable heat treatment.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on illustrated embodiments. FIG. 1 is a schematic sectional view showing a vertical single-wafer heat treatment apparatus according to an embodiment of the present invention.
FIG. 3B is a perspective view and a sectional view showing the thermal buffering placed on the tip portion of the wafer holder, and FIGS. 3 and 4 are diagrams for explaining a high temperature short time heat treatment method using the thermal buffering. It is a figure.

A vertical core tube 10 made of a cylindrical quartz tube.
A heater 12 for controlling the temperature in the core tube 10 is provided around the
a, 12b, 12c are installed. Also, the core tube 1
At the upper part of 0, there is an inlet 14 for supplying an atmospheric gas such as O ₂ (oxygen), N ₂ (nitrogen), Ar (argon). Further, the wafer holder 16 made of quartz is loaded with a semiconductor wafer 18 made of, for example, a Si substrate at its tip, and a cylindrical thermal buffer ring 20 is placed so as to be located on the outer periphery of the semiconductor wafer 18. It has become. In addition, as the material of the thermal buffering 20,
Polycrystalline Si or SiC having the same thermophysical properties as the Si substrate is used.

Further, the wafer holder 16 is moved up and down by a driving device (not shown), and the semiconductor wafer 18 loaded at the tip of the wafer holder 16 is externally attached to the core tube together with the thermal buffer ring 20 located on the outer periphery thereof. 10
It is designed to be carried in or carried out from the inside of the core tube 10. Further, although not shown, a thermal buffer ring attaching / detaching device for placing the thermal buffer ring 20 on the tip of the wafer holder 16 or detaching it from the wafer holder 16 is installed below the core tube 10. Further, at the end of the wafer transfer device installed between the front and rear steps, a wafer handling device for loading the semiconductor wafer 18 on the tip of the wafer holder 16 or taking it out from the tip of the wafer holder 16 is installed.

Next, a high-temperature short-time heat treatment method performed by using this vertical type single-wafer heat treatment apparatus will be described. First, one semiconductor wafer 18 transferred by a wafer transfer device (not shown) from the previous step is loaded on the tip of the wafer holder 16 by a wafer handling device (not shown). At this time, the thermal buffering 20
Is held in the space between the core tube 10 and the wafer holder 16 by the arm 22 of the thermal buffering attachment / detachment device so as not to hinder the wafer loading by the wafer handling device (see FIG. 3A). ).

Next, the wafer holder 16 is lifted by a driving device (not shown), and the wafer holder 16
Move to a position where the thermal buffering 20 is placed on the tip. And the arm 22 of the thermal buffering attachment / detachment device.
Is moved to release the sandwiching of the thermal buffer ring 20.
Thus, the thermal buffer ring 20 is installed on the outer periphery of the semiconductor wafer 18 (see FIG. 3B).

Then, the wafer holder 16 is again raised by the driving device, and the semiconductor wafer 18 is loaded into the core tube 10 from the outside. At this time, the inside of the core tube 10 to which the predetermined atmospheric gas is supplied is heated by the heaters 12a, 12a.
It is set to a predetermined high temperature by b and 12c. Therefore, the semiconductor wafer 18 loaded at the tip of the wafer holder 16 is heated from room temperature to a predetermined high temperature with the thermal buffer ring 20 positioned on the outer periphery thereof. Then, high temperature short time heat treatment is performed at this predetermined high temperature (see FIG. 3C).

Next, when this high-temperature short-time heat treatment is completed, the thermal buffering 20 is applied to the outer periphery of the semiconductor wafer 18.
The wafer holder 16 is moved down by the driving device while keeping the position. In the middle of this descent, the arm 22 of the thermal buffering attachment / detachment device is moved again to the position where the thermal buffering 20 is clamped. Of course, the movement of the arm 22 may be carried out before the time when the thermal buffer ring 20 is detached from the wafer holder 16 (see FIG. 4A).

Then, the semiconductor wafer 18 is transferred to the core tube 10.
When the wafer holder 16 is carried out, the lowering of the wafer holder 16 is temporarily stopped, and the semiconductor wafer 18 is air-cooled while the thermal buffering 20 is still positioned on the outer periphery.
The internal high temperature is cooled to room temperature (see FIG. 4 (b)). It should be noted that the semiconductor wafer 18 is cooled not to room temperature but to a predetermined temperature higher than room temperature as long as thermal stress does not occur in the semiconductor wafer 18 due to subsequent cooling. At this time, the wafer holder 16
It is not always necessary to stop the descending by controlling the descending speed of.

Then, the wafer holder 16 is lowered again, and the thermal buffer ring 20 is held by the arm 22 of the thermal buffer ring attaching / detaching device at the same position as shown in FIG. 3B. Then, in this state, the wafer holder 16 is further lowered to separate the thermal buffering 20 from the wafer holder 16 (FIG. 4C).
reference).

Subsequently, although not shown, the semiconductor wafer 18 is taken out from the tip of the wafer holder 16 by a wafer handling device, and then transferred to the next step by the wafer transfer device. As described above, according to the present embodiment, when the semiconductor wafer 18 is loaded into the core tube 10 from the outside and heated from room temperature to a predetermined high temperature, the thermal buffering 20 is positioned on the outer periphery of the semiconductor wafer 18. By functioning as a heat buffer between the heating medium and the semiconductor wafer 18,
Deprives the heat energy absorbed by the semiconductor wafer 18
Suppresses the temperature rise from the peripheral area. Therefore, it is possible to eliminate the temperature nonuniformity between the peripheral portion and the central portion within the surface of the semiconductor wafer 18 due to the temperature rise during heating.

After the completion of the high-temperature short-time heat treatment, the semiconductor wafer 18 is carried out from the inside of the core tube 10 to the outside, and when it is cooled from the high temperature inside the core tube 10 to the room temperature, it is exposed to the outer periphery of the semiconductor wafer 18. By keeping the thermal buffering 20 in the position, the thermal buffering 20
Temporarily functions as a heat insulating material for the semiconductor wafer 18 against the outside air, so that heat energy is applied to the semiconductor wafer 18 and heat escape from the peripheral portion of the semiconductor wafer 18 is suppressed. Therefore, it is possible to eliminate the temperature non-uniformity between the peripheral portion and the central portion within the surface of the semiconductor wafer 18 when the temperature decreases during cooling.

Therefore, it is possible to suppress the occurrence of wafer warpage and slip due to thermal stress during heating and cooling of the semiconductor wafer 18, and to realize stable high-temperature short-time heat treatment. Further, the attachment / detachment of the thermal buffering 20 is performed by the arm 22 of the thermal buffering attaching / detaching device.
Wafer holder 16 and core tube 1 during wafer loading
By performing the operation in the space between 0 and 0, it does not hinder the loading or unloading of the semiconductor wafer 18 into / from the wafer holder 16 by the wafer handling device, and thus the conventional wafer transfer device and wafer handling device can be used as they are. It has the advantage that it can be used.

In the above embodiment, the heat buffer ring 20 has a cylindrical shape, but the shape of the heat buffer ring is not limited to this, and various shapes can be used. For example, as shown in FIG. 5, it may be a disk-shaped thermal buffer ring 24. However, the size thereof needs to be able to be carried into the core tube 10 while being positioned on the outer periphery of the semiconductor wafer 18. When the shape of the thermal buffer ring is changed, the shape of the tip end portion is changed so as to mount the disk-shaped thermal buffer ring 24 corresponding to the change.
In some cases, 6 must be used.

A semiconductor wafer 1 made of a Si substrate
On the other hand, although the material of the thermal buffering 20 is polycrystal Si or SiC having the same thermophysical properties as Si, the thermal buffering material or the heat insulating material is required depending on the material of the wafer. Thermal buffering 20 according to its function as
Various materials can be used as the material. Further, in the above-described embodiment, the attachment / detachment of the thermal buffer ring 20 is performed by the thermal buffer attachment / detachment device in the space between the wafer holder 16 and the core tube 10 at the time of wafer loading. There are various methods of attachment and detachment. For example, a thermal buffering attachment / detachment device may be used in which the semiconductor wafer 18 is loaded into the wafer holder 16 and then the thermal buffering 20 is placed on the wafer holder 16 in the same state. Alternatively,
By improving the wafer handling device so that the semiconductor wafer 18 can be loaded with the thermal buffer ring 20 placed on the tip of the wafer holder 16, the thermal buffer ring 20 is fixed to the tip of the wafer holder 16. May be.

Further, in the above-mentioned embodiment, the case where the semiconductor wafer 18 is heat-treated at a high temperature for a short time has been described. However, the heat treatment is not limited to such heat treatment, and the non-uniformity of the temperature in the plane of the wafer-shaped sample is eliminated, The present invention is widely applied to heat treatments that need to suppress the generation of stress.

[0031]

As described above, according to the present invention, when the wafer is loaded into the core tube from the outside and heated from the external temperature to the high temperature in the core tube, the thermal buffering is installed on the outer periphery of the wafer. By functioning as a heat buffer between the heating medium and the wafer and suppressing the temperature rise from the peripheral portion of the wafer, the temperature between the peripheral portion and the central portion in the wafer surface during heating is suppressed. The non-uniformity of can be eliminated.

After high temperature heat treatment in the core tube,
When the wafer is unloaded from the core tube to the outside and is cooled from the high temperature in the core tube to the external temperature, the thermal buffering is installed on the outer periphery of the wafer to temporarily function as a heat insulating material. Since the heat is prevented from escaping from the peripheral portion, it is possible to eliminate the non-uniformity of the temperature between the peripheral portion and the central portion within the wafer surface during cooling.

As a result, it is possible to prevent the wafer from warping or slipping due to thermal stress during heating and cooling of the wafer, and to realize stable high-temperature short-time heat treatment. Therefore, the technique for forming a shallow junction is improved, which contributes to higher integration and higher speed of the LSI.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a vertical single-wafer heat treatment apparatus according to an embodiment of the present invention.

2A and 2B are a perspective view and a cross-sectional view showing a thermal buffering mounted on a tip portion of a wafer holder of the vertical single-wafer heat treatment apparatus of FIG.

FIG. 3 is a diagram (No. 1) for explaining a high-temperature short-time heat treatment method using the vertical single-wafer heat treatment apparatus of FIG.

FIG. 4 is a diagram (No. 2) for explaining the high temperature short time heat treatment method using the vertical single-wafer heat treatment apparatus of FIG. 1;

FIG. 5 is a perspective view and a cross-sectional view showing a thermal buffering according to another embodiment of the present invention.

FIG. 6 is a diagram for explaining a high-temperature short-time heat treatment method using a conventional vertical single-wafer heat treatment apparatus.

[Explanation of symbols]

 10 ... Reactor tube 12a, 12b, 12c ... Heater 14 ... Atmosphere gas supply inlet 16 ... Wafer holder 18 ... Semiconductor wafer 20 ... Thermal buffering 22 ... Thermal buffering attachment / detachment device arm 24 ... Thermal buffering 26 ... Wafer holder 30 ... Reactor core tubes 32a, 32b, 32c ... Heater 34 ... Atmosphere gas supply inlet 36 ... Wafer holder 38 ... Semiconductor wafer

Claims (3)

[Claims] 1. A wafer is loaded into the furnace core tube from the outside, and when the wafer is heated from an external temperature to a high temperature in the furnace tube, the wafer is heated with a thermal buffering installed on the outer periphery thereof. After performing a heat treatment on the wafer at a high temperature in the core tube for a predetermined time, the wafer is carried out of the core tube to the outside, and the wafer is cooled from the high temperature in the core tube to an external temperature. At this time, the heat treatment method is characterized in that the wafer is cooled to a predetermined temperature in a state where a thermal buffering is provided on the outer periphery of the wafer. 2. A wafer is loaded on the wafer holder, a thermal buffer ring is placed on the wafer holder so that the thermal buffer ring is located on the outer periphery of the wafer, and the wafer holder is driven. The wafer and the thermal buffering are loaded into the furnace core tube from the outside, and in a state where the thermal buffering ring is located on the outer periphery of the wafer, the wafer is heated from an external temperature to a high temperature in the furnace core tube, After performing a heat treatment on the wafer for a predetermined time at a high temperature in the core tube, drive the wafer holder, carry out the wafer and the thermal buffering from the inside of the core tube to the outside, to the outer periphery of the wafer. With the thermal buffering in place, cooling the wafer from a high temperature in the furnace tube to a predetermined temperature, A method for heat treatment, comprising: removing the thermal buffering from the wafer holder, and then taking out the wafer from the wafer holder. 3. A vertical core tube, a heater installed around the core tube to set a predetermined high temperature inside the core tube, a wafer holder, and wafer handling means for loading a wafer into the wafer holder. A thermal buffer ring attaching / detaching means for placing the thermal buffer ring on the wafer holder so as to be located on the outer periphery of the wafer loaded in the wafer holder, or for detaching the thermal buffer ring from the wafer holder; A wafer holder is moved up and down, and the wafer loaded in the wafer holder and the thermal buffering located on the outer periphery of the wafer are carried into the furnace core tube from the outside, or a driving means for carrying out the furnace core tube to the outside. A heat treatment apparatus having.