JPH0555195A - Thermal process apparatus for semiconductor wafer - Google Patents

Abstract

PURPOSE:To reduce the variation in the thickness of oxide films and layer resistances by reducing the fluctuation of the temperature in a furnace due to the reaction heat of the gas. CONSTITUTION:A core tube 1 is heated by three heaters, a front heater 2, a central heater 3, and a rear heater 4a with a built-in lamp. The temperatures of these heaters are raised or lowered in accordance with the output voltage from a temperature controller 5. Particularly, the rear heater 4a with the built-in lamp comprises a resistance heating type heater 9 and an infrared lamp 10, and controls the temperature in the furnace by changing the output of the infrared 10 lamp in accordance with the reaction heat of the gas while keeping the output of the resistance heating type heater 9 at a constant level.

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 for semiconductor wafers, and more particularly to a heat treatment apparatus for performing thermal oxidation and thermal diffusion.

[0002]

2. Description of the Related Art In a conventional heat treatment apparatus, a furnace core tube 1 is resistance-heated by three heaters of a front heater 2, a center heater 3 and a rear heater 4b as shown in the configuration diagram of FIG. The heater is controlled by the temperature controller 5. The program controller 7 reads the data in the program memory 8 and controls the temperature controller 5 and the gas supply controller 6. At this time, the front heater 2, the center heater 3 and the rear heater 4b are usually arranged such that the resistance heater 9 surrounds the furnace core tube 1 as shown in the side view (a) and sectional view (b) of FIG. It has become.

For example, when performing steam oxidation on a silicon substrate, various measures are taken to reduce the variation in oxide film thickness in the furnace. In steam oxidation, hydrogen is usually supplied at a predetermined temperature in an oxygen atmosphere. At this time,
Based on the temperature during steam oxidation (during hydrogen supply),
The temperature distributions in the furnace before and after the hydrogen supply and during the hydrogen supply are shown in FIGS. 7A and 7B, respectively. Further, particularly with respect to the gas supply side, the temperature changes drastically with time, and as shown in FIG. 7C, the temperature changes near the rear heater increase with time. On the contrary, if the temperature when the hydrogen is not supplied is used as a reference, the temperature distributions in the furnace before and after the hydrogen supply and during the hydrogen supply are as shown in FIGS. 8 (a) and 8 (b), respectively. 8 (c). In this case, the temperature change near the rear heater may be 30 ° C. or higher.

When the temperature distribution in the furnace changes as described above and the thermal history is different and the oxide film thickness varies in the furnace, generally, a method of previously shifting the output of the heater from the standard value is used. The amount of the deviation depends on the process conditions and the position of the heater. There is also a method of changing the combustion method of hydrogen, and in particular, an apparatus called an external combustion apparatus is used to introduce oxygen and hydrogen into the furnace core tube after the reaction to suppress the temperature change in the furnace due to the heat of reaction.

[0005]

The conventional heat treatment apparatus for semiconductor wafers has the following problems. First,
This is a thermal oxidation method that shifts the heater output from the standard value in advance.This method can form an oxide film with small variations under certain specified conditions, but it can be done by changing the hydrogen supply time within the wafer furnace. The position-dependent thermal history changes, and the variation in the oxide film thickness increases. Further, when the ion implantation region is activated at the same time as the oxidation, the difference in thermal history becomes the difference in layer resistance. These phenomena are also the same in the case of thermal diffusion, which causes variations in diffusion layer resistance.

When an external combustion device is used, there is a risk of insufficient ignition of hydrogen-oxygen at room temperature.
Since the device configuration becomes complicated, there is a drawback that maintenance becomes difficult. Furthermore, in the conventional resistance heating type heater, the temperature rising / falling speed is about 10 ° C./minute,
Especially when hydrogen burns in the furnace core tube and the temperature rises sharply,
Even if the heater output is reduced, the temperature does not fall and it is impossible to maintain a constant temperature.

[0007]

According to the heat treatment apparatus for semiconductor wafers of the present invention, an infrared lamp is incorporated in a resistance heating type rear heater part, and the output of this rear heater is made constant, depending on the reaction gas temperature in the furnace core tube. And means for controlling the output of the infrared lamp.

[0008]

The present invention will be described below with reference to the drawings. 1 is a device configuration diagram of a first embodiment of the present invention. The furnace core tube 1 is heated by three heaters including a front heater 2, a center heater 3 and a lamp-equipped rear heater 4a. These heaters can raise and lower the temperature according to the output voltage from the temperature control device 5. In particular, as shown in the side view (a) and cross-sectional view (b) of FIG. 2, the rear heater 4a with a built-in lamp has an infrared lamp 10 arranged in a normal resistance heating type heater 9 and the resistance heating type heater 9 By changing the output of the infrared lamp 10 while keeping the output of 1 constant, it is possible to rapidly raise and lower the temperature.

The program memory 8 stores data on process conditions such as temperature, processing time and gas.
The program controller 7 reads the data and controls the temperature control device 5 and the gas supply control device 6. For example, in the case of performing steam oxidation, the output of the infrared lamp 10 is kept at a constant value before the hydrogen supply, and the output of the infrared lamp 10 is gradually decreased at the same time when the hydrogen supply is started. At that time, the output of the infrared lamp 10 is lowered in accordance with the temperature rise due to the reaction heat of hydrogen and oxygen, but the output of the infrared lamp is set to zero when the inside of the furnace is in a steady state.
Next, at the same time when the hydrogen supply is completed, the output of the infrared lamp 10 is gradually increased to the value before the hydrogen supply.

As a result, as shown in FIG. 3, the temperature in the vicinity of the lamp-incorporated rear heater 4a can be kept constant and the fluctuation range can be suppressed within ± 1 ° C. The output data of the infrared lamp 10 shown in FIG. 3 is previously input to the program memory 8. This data is obtained by supplying hydrogen with the output of the infrared lamp 10 set to zero, measuring the time-dependent change in the temperature near the lamp built-in rear heater 4a, and compensating for the difference from the steady-state temperature during hydrogen supply. You can set it as follows.

FIG. 4 is a block diagram of an apparatus according to the second embodiment of the present invention. The configuration is almost the same as that of the first embodiment, but instead of inputting the detailed temperature data to the program memory 8, the front temperature sensor 11, the center temperature sensor 12, and the rear temperature sensor 13 are used to control the temperature due to the reaction heat before and after the hydrogen supply. The change is directly measured, and the temperature control device 5 adjusts the output of the infrared lamp 10 of the lamp built-in rear heater 4a to maintain a constant temperature. Since the temperature is directly measured in the second embodiment, the temperature followability is improved.

[0012]

As described above, according to the present invention, the temperature can be kept constant even when the temperature fluctuates during oxidation such as steam oxidation. Therefore, the film thickness of the silicon oxide film depends on the position in the furnace. It has an effect that the property can be reduced. At the same time as steam oxidation, activation of the ion implantation region,
When impurities are driven in, the difference in the thermal history depending on the position in the furnace can be reduced, so that the variation in the layer resistance of the impurity layer is reduced and the h _{FE of} the bipolar transistor, the V _{T of} the MOS transistor, the resistance value, etc. are stabilized. .. Moreover, since the present invention does not use an external combustion device, maintainability is not impaired and safety is high.

[Brief description of drawings]

FIG. 1 is a device configuration diagram of a first embodiment of the present invention.

2A and 2B are diagrams showing a rear heater with a built-in lamp, in which FIG. 2A is a side view and FIG. 2B is a sectional view.

FIG. 3 is a diagram showing changes over time in the output of an infrared lamp and the temperature in the vicinity of a lamp built-in rear heater in steam oxidation.

FIG. 4 is a device configuration diagram of a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional device.

6A and 6B are views showing a conventional resistance heater, in which FIG. 6A is a side view and FIG. 6B is a sectional view.

FIG. 7 is a diagram showing a case where the temperature during hydrogen supply is used as a reference in steam oxidation. FIG. 7A shows a temperature distribution before and after hydrogen supply, and FIG. 7B shows a temperature distribution during hydrogen supply. FIG. 6C is a diagram showing changes in temperature with time.

FIG. 8 is a diagram showing a case where the temperature before and after hydrogen supply is used as a reference in steam oxidation. FIG. 8A shows a temperature distribution before and after hydrogen supply, and FIG. 8B shows a temperature distribution during hydrogen supply. FIG. 6C is a diagram showing changes in temperature with time.

[Explanation of symbols]

 1 Furnace Core Tube 2 Front Heater 3 Center Heater 4a Lamp Built-in Rear Heater 4b Rear Heater 5 Temperature Control Device 6 Gas Supply Control Device 7 Program Controller 8 Program Memory 9 Resistance Heating Heater 10 Infrared Lamp 11 Front Temperature Sensor 12 Center Temperature Sensor 13 Rear temperature sensor

Claims (1)

[Claims] 1. A heat treatment apparatus for semiconductor wafer, wherein a furnace core tube is heated by a resistance heating type front heater, a center heater, and a rear heater, respectively, and a temperature controller and a gas supply controller are controlled by a program controller. A heat treatment apparatus for semiconductor wafers, characterized in that an infrared lamp is built in, the output of the rear heater is made constant, and the output of the infrared lamp is controlled according to the reaction gas temperature in the furnace core tube.