JPH07321059A - Device and method for heat treatment - Google Patents

Abstract

PURPOSE:To provide a heat-treating device which improves a heat-up and cooling-down speed while reducing a stress, which is applied to a substrate, and a method of heat-treating. CONSTITUTION:A heat-treating device is provided with a substrate holding means 11 for holding a substrate 9 to be heat-treated, a heat source 6 arranged at a prescribed interval between the means 11 and the source 6, a reflective plate 1 for making radiant heat, which is radiated from the heat source 6, reflect toward the substrate 9 and a first moving means 3 for moving the plate 1 and the plate 1 is moved by the means 3 to adjust the amount of the radiant heat to reach the substrate 9, whereby the heat-treating temperature of the substrate 9 is adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus and a heat treatment method. The present invention relates to a heat treatment apparatus capable of rapidly raising and lowering a temperature in a heat treatment apparatus for a single wafer type semiconductor substrate and the like, and a heat treatment apparatus suitable for a manufacturing process in which a substrate temperature is changed during heat treatment.

[0002]

2. Description of the Related Art Conventionally, various heat treatment apparatuses have been used for forming a diffusion layer, a silicon oxide film, a silicon nitride film, etc. on a semiconductor wafer or a glass substrate. In these apparatuses, a predetermined heat treatment is generally performed by heating a substrate to be heat-treated contained in a reaction vessel (heating chamber) and introducing an inert gas or a reactive gas into the vessel.

The conventional temperature adjustment method is to adjust the temperature of the substrate to be processed by adjusting the electric power supplied to the electric furnace. That is, when the heat source of the electric furnace is a combination of a carbon heater or RF coil and a heating medium, the carbon heater or RF
The temperature is adjusted by adjusting the current flowing through the coil. The temperature control is generally PID control or the like.

However, in the heat treatment apparatus of the type for controlling the electric power of the heat source as in the prior art, there is a problem that the heat capacity of the heat source is relatively large and it takes a relatively long time to raise and lower the temperature. Therefore, it has become very difficult to form a shallow diffusion layer, which is required for high integration of a semiconductor integrated circuit.

Here, in order to realize high-speed heating and cooling, a single-wafer type heat treatment apparatus has been developed which mainly adjusts the temperature only by raising and lowering the substrate holder. This technique is disclosed in detail in USP 4,857,689. That is, the electric power supplied to the heat source and the output of the heat source are fixed, and the temperature is adjusted exclusively by raising and lowering the substrate holder on which the substrate to be processed is mounted. The substrate temperature rises when the substrate is brought close to the heat source, and the substrate temperature drops when the substrate is moved away from the heat source. As a result, the heat capacity of the heat source etc. does not become a problem at all for raising and lowering the temperature,
By raising and lowering the substrate at high speed, temperature control can be performed at high speed.

However, in the heat treatment apparatus of the type in which the substrate holder is moved, it is necessary to apply a considerable acceleration to the substrate during the heat treatment in order to adjust the temperature at high speed. The movement of the substrate and the application of acceleration during heat treatment are
A great deal of stress is applied to the substrate, and in some cases, if the substrate is a semiconductor substrate, problems such as transfer occur. This also contributes to lowering the yield. In addition, there is a certain limit to the movement of the substrate holder without stressing the substrate, and this problem limits the rate of temperature increase / decrease.

[0007]

As described above, in the conventional substrate holder movement type heat treatment apparatus, there are problems that a large amount of stress is applied to the substrate and that there is a certain limit in raising and lowering the temperature. . It is an object of the present invention to provide a heat treatment apparatus and a heat treatment method thereof, in which the above-mentioned drawbacks are eliminated and the stress applied to the substrate is reduced while the temperature rising / falling rate is improved.

[0008]

In order to achieve the above object, in the present invention, a substrate holding means for holding a substrate to be heat treated, a heat source arranged at a predetermined distance from the substrate holding means, and a heat source from the heat source. The radiant heat to be heat-treated is provided with a reflecting plate that reflects the emitted radiant heat toward the substrate to be heat-treated, and a first moving unit that moves the reflecting plate. Provided is a heat treatment apparatus characterized in that the heat treatment temperature of a substrate to be heat-treated is adjusted by adjusting the amount reaching the substrate.

Further, the first desirable is a reflector for reflecting radiant heat emitted from heat sources arranged at a predetermined interval from the substrate holding means for holding the substrate to be heat treated toward the substrate to be heat treated. And a step of moving the reflection plate to a second position in accordance with the second desired heat treatment temperature.
Also, there is provided a heat treatment method characterized in that the temperature of the substrate to be heat treated is adjusted by moving the reflector according to the second desired heat treatment temperature.

[0010]

When the means provided by the present invention is used, the heat treatment temperature is adjusted solely by moving the reflection plate, and for example, by moving the reflection plate away from the substrate, the radiant heat reaching the substrate to be heat treated is reduced, and the temperature of the substrate is reduced. By lowering the temperature and, conversely, bringing the reflection plate closer to the substrate, the radiant heat reaching the substrate to be heat-treated is increased and the temperature of the substrate is raised.
As a result, it is not necessary to move the substrate holding means at high speed, and the stress applied to the substrate is reduced. Further, the temperature can be adjusted at a high speed by moving the reflecting plate at a high speed (and by performing the movement together with the movement of the substrate holder).

[0011]

EXAMPLES Examples of the present invention will be described with reference to FIGS. 1 to 7. The heat treatment apparatus of the present invention has the configuration shown in FIG. That is, the movable reflecting plate 1, the holding shaft 2 connected to the movable reflecting plate 1, the first moving means 3, the peripheral device 4 surrounding them, the upper fixed reflecting plate 5, the heat source 6, the reaction tube 7, Shielding plate 8, substrate holding base 11 on which semiconductor substrate 9 is mounted and connected to substrate holding shaft 10, and lower fixed reflecting plate 1
2, gas inlet 13, substrate inlet / outlet 14, second moving means 16, reaction inner tube 17, temperature sensor 18,
It is composed of a control device 19.

The movable reflector 1 is made of quartz (more preferably white quartz) covered with a SiC thin film. As another method, it is possible to use a member having a high reflectance and a low absorptance for heat radiation (for example, stainless steel, aluminum, etc.).

The first moving means 3 uses a servomotor and a ball screw to drive the holding shaft 2 of the movable reflecting plate 1 to move it. The peripheral device 4 is set to a predetermined temperature by a coolant, cooling water, etc., and divides a first temperature region having a lower temperature than a high temperature region near a heat source, which will be described later. The specific size of the peripheral device 4 is, for example, that the diameter of the semiconductor substrate is 150 mm.
Assuming that the peripheral device 4 has a diameter of 400 mm and a height of 500
A cylindrical shape having a thickness of about 5 mm and a thickness of about 5 mm is suitable. Aluminum oxide or the like is suitable for the member. The diameter of the movable reflection plate 1 at this time is preferably about 390 mm.

The heat source 6 is composed of a resistance heater, a heating medium heated by an RF coil, and the like, and is further adjusted to a constant temperature by cooling water or the like. However,
The temperature is not changed during the heat treatment.

The surface temperature of the movable reflection plate 1 is a temperature determined by the positional relationship among the upper fixed reflection plate 5, the lower fixed reflection plate 12, the heat source 6 and the movable reflection plate 1. That is,
When the movable reflector 1 is located at the uppermost position, the surface temperature is the lowest, and when the movable reflector 1 is located at the lowest part, the surface temperature is the highest. The heat is transferred from the movable reflector 1 to the substrate 9 by reflected heat, diffused heat, and heat radiation from the reflector.

Reaction tube 7, reaction inner tube 17 and gas inlet 1
With the configuration of 3, the reaction gas (predetermined reaction gas in the thin film deposition step / oxide film formation step) or the inert gas (eg, argon gas in the heat treatment after ion implantation) flows from the upper side to the lower side of the substrate 9. . By arranging the substrate such that the axis of the substrate is vertical, a low particle environment can be achieved.

The shield plate 8 serves to shield the radiation heat directly from the heat source 6 to the substrate 9. Therefore, the heating of the substrate 9 is rate-limited by the heat radiation and the heat diffusion from the fixed reflecting plates 5 and 12 and the movable reflecting plate 1 to the substrate 9,
The temperature adjustment by the movable reflection plate 1 can be performed more accurately.

The substrate entrance / exit 14 is of a load-lock type or an open-type, for example, and the substrate holding table 11 has the substrate holding shaft 10 and the second moving means 16 (similar to the first moving means 3). The substrate 9 is loaded and unloaded from the outside of the heat treatment apparatus when the substrate 9 is moved to the lowermost part by the above (including the like).

The temperature sensor 18 constantly monitors the surface temperature of the substrate 9, and the detection output is input to the controller 19. The control device 19 compares the signal in corresponding to the set temperature input from the outside with the signal sense which is a detection output, outputs the control signal cont, and transfers this to the first moving means 3. The first moving means 3 is controlled by negative feedback control such as PID control. More specifically, when the detected temperature is lower than the set temperature, the movable reflector 1 is moved to the lower part, and when the detected temperature is higher than the set temperature, the movable reflector 1 is moved to the upper part. .

With the configuration as described above, the heat treatment temperature is adjusted solely by moving the movable reflecting plate. For example, by moving the movable reflecting plate away from the substrate, the radiant heat reaching the substrate is reduced and the temperature of the substrate is reduced. And, conversely, by bringing the movable reflection plate closer to the substrate, the radiant heat reaching the substrate is increased and the temperature of the substrate is raised. As a result, it is not necessary to move the substrate holder at high speed, and the stress applied to the substrate is reduced. Further, the temperature adjustment can be performed at high speed by moving the movable reflecting plate at high speed (further, by performing it together with the movement of the substrate holding table as described later).

Next, the method of using the heat treatment apparatus provided by the present invention will be further explained. The step of raising the temperature of the substrate before the start of the heat treatment will be described with reference to FIG. That is, the substrate holder 11 is lowered to the lowermost position, the substrate 9 is mounted on the substrate holder 11 through the substrate inlet / outlet 14, and then the substrate holder 11 is raised at the speed V2 (t). At the same time, the movable reflector 1 descends at the speed V1 (t). As a result, when the temperature is raised, the temperature is raised faster than the temperature rise corresponding to the rise of the substrate holding table 11. That is, the substrate is heated at a high rate of temperature increase corresponding to the relative speed V1 (t) + V2 (t) between the movable reflector 1 and the substrate holder 11.

Next, regarding the change of the set temperature during processing,
This will be described with reference to FIG. That is, the substrate holding table 11 on which the substrate 9 is mounted is fixed to the uppermost part of the reaction tube 7,
The movable reflection plate 1 moves up and down as the set temperature changes. For example, when changing the set temperature from T1 (low temperature) to T2 (cooling), the signal in and the signal sense input from the outside are compared in the control device 19. The temperature sensor 18 constantly monitors the surface temperature of the substrate 9, and the detection output is input to the control device 19. The control device 19 compares the signal in corresponding to the set temperature input from the outside with the signal sense which is a detection output, outputs the control signal cont, and transfers this to the first moving means 3. As described above, the first moving means 3 is controlled by negative feedback control such as PID control.
To control. In this case, when the detected temperature is lower than the set temperature, the movable reflector 1 is moved to the lower part and 1 to the upper part at the speed V1 (t).

Next, the step of lowering the temperature of the substrate at the end of the heat treatment will be described with reference to FIG. That is, the substrate holding table 11 descends to the lowermost portion at a speed V2 (t). At the same time, the movable reflector 1 moves up at the speed V1 (t). As a result, when the temperature is lowered, the temperature is lowered faster than the temperature corresponding to the lowering of the substrate holding table 11. That is, the substrate is cooled at a high temperature decreasing rate corresponding to the relative speed V1 (t) + V2 (t) between the movable reflecting plate 1 and the substrate holder 11.

The manner in which the rate of temperature increase and the rate of temperature decrease are improved will be described with reference to FIG. [FIG. 5] (a) shows how the substrate temperature changes with time during temperature rise. That is,
At time t0, the substrate is mounted, the substrate holding table 11 starts to rise, and the substrate temperature rises from T0 (eg 20 ° C.) to T1 (eg 800 ° C.). 20 is the set temperature. 21 is the situation of temperature rise in this embodiment,
It can be seen that the temperature is raised faster than the temperature change 22 of the conventional example. [FIG. 5] (b) shows how the substrate temperature changes with time when the temperature is lowered. That is, at time t0, the substrate holding table 11 starts to descend, and the substrate temperature rises from T1 (for example, 800 ° C.) to T0 (for example, 20 ° C.). Reference numeral 21 indicates the temperature drop situation in this embodiment, and it can be seen that the temperature is lowered faster than the temperature change 22 of the conventional example.

Next, an example in which the introduced gas, the processing temperature and the like are variously changed during the heat treatment will be described with reference to FIGS. 6 and 7. [FIG. 6] is an example showing the timing of gas supply and the time change of the heat treatment temperature, and [FIG. 7] is a cross-sectional view showing the manufacturing steps in the order of steps. A silicon substrate 41 in which a BAsSG film (boron / arsenic silicate glass) 42 containing boron and arsenic in an oxide film is deposited is mounted on a substrate holding table and raised to a certain height in the reaction tube, and the substrate is heated to 500 ° C. Hold. At this time, G1 is emptied and nitrogen gas is supplied into the reaction tube. Then, the substrate temperature is set to 800 ° C. at a temperature rising rate of 100 ° C./second. The temperature change at this time is performed by simultaneously raising the substrate holder and lowering the reflector. G1 is closed and the supply of nitrogen gas is stopped. At the same time, G2 is emptied and closed after a lapse of a predetermined time to supply 10% of hydrogen gas into the reaction tube. Then, the substrate temperature is set to 1000 ° C. at a heating rate of 100 ° C./sec. At this time, the temperature is changed only by lowering the reflector. Hold in this state for a while,
Boron is diffused from the BAsSG film 42 to form a P-type diffusion layer region 43 ([FIG. 7] (b)). Then 50
The substrate temperature is set to 800 ° C. by lowering the temperature at a rate of ° C./sec. At this time, the temperature is lowered only by raising the reflector. In this state, oxygen is supplied from G3 to oxidize arsenic to facilitate diffusion into the silicon substrate. Again 100
The substrate temperature is set to 950 ° C. by raising the temperature by ℃ / sec.
At this time, the temperature is raised only by lowering the reflector. In this state,
Arsenic is diffused from the BAsSG film 42 to form an N-type diffusion layer region 44 ([FIG. 7] (c)). Then, the reflecting plate is raised and the substrate holder is lowered until the substrate temperature becomes 500 ° C. or lower. Further, the substrate holder is lowered to the lowermost portion, and the substrate is taken out.

As described above, it can be understood that the heat treatment apparatus and the heat treatment method provided by the present invention are very suitable for executing a process including a plurality of steps in the same electric furnace.

[0027]

When the means provided by the present invention is used, the heat treatment temperature is adjusted solely by moving the reflector, and for example, by moving the reflector away from the substrate, the radiant heat reaching the substrate to be heat treated is reduced, By lowering the temperature of the substrate and, conversely, bringing the reflection plate closer to the substrate, the radiant heat reaching the substrate to be heat-treated is increased and the temperature of the substrate is raised. As a result, it is not necessary to move the substrate holding means at high speed, and the stress applied to the substrate is reduced. Further, the temperature can be adjusted at a high speed by moving the reflecting plate at a high speed (and by performing the movement together with the movement of the substrate holder).

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing a situation during operation of the embodiment of the present invention.

FIG. 3 is a diagram showing a situation during operation of the embodiment of the present invention.

FIG. 4 is a diagram showing a situation during operation of the embodiment of the present invention.

FIG. 5 is a diagram showing an effect of the present invention.

FIG. 6 is a diagram showing an example of use of the heat treatment apparatus of the present invention.

FIG. 7 is a cross-sectional view showing a manufacturing process of a semiconductor device using the heat treatment apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Movable reflection plate 2 Holding shaft 3 First moving means 4 Perimeter 5 Upper fixed reflection plate 6 Heat source 7 Reaction tube 8 Shielding plate 9 Semiconductor substrate 10 Substrate holding shaft 11 Substrate holding table 12 Lower fixed reflection plate 13 Gas introduction port 14 Substrate entrance / exit 16 Second moving means 17 Reaction inner tube 18 Temperature sensor 19 Controller

Claims (4)

[Claims] 1. A substrate holding means for holding a substrate to be heat-treated, a heat source arranged at a predetermined distance from the substrate holding means, and radiant heat emitted from the heat source toward the substrate to be heat-treated. A reflecting plate for reflecting and a first moving unit for moving the reflecting plate are provided, and the amount of the radiant heat reaching the substrate to be heat-treated is adjusted by moving the reflecting plate by the first moving unit. Accordingly, the heat treatment apparatus is characterized in that the heat treatment temperature of the substrate to be heat treated is adjusted. 2. The heat treatment apparatus according to claim 1, further comprising second moving means for moving the substrate holding means. 3. A shield wall is provided between the substrate holding means and the heat source, and the shield wall blocks direct heat radiation from the heat source to the substrate to be heat-treated. The heat treatment apparatus according to claim 1. 4. A first reflection plate for reflecting radiant heat emitted from a heat source arranged at a predetermined distance from a substrate holding means for holding a substrate to be heat treated toward the substrate to be heat treated. A step of moving to a first position according to a desired heat treatment temperature; and a step of moving the reflection plate to a second position according to a second desired heat treatment temperature.
And a step of moving the reflecting plate according to the first and second desired heat treatment temperatures to adjust the temperature of the substrate to be heat treated. .