JPH01220435A - Vapor growth furnace - Google Patents

Abstract

PURPOSE:To easily execute the setting of a processing temperature even if a film is formed due to a processing of the inner face of a process tube by using the tube having lower optical transmittivity than that of a transparent material. CONSTITUTION:A heater 6 is provided on the periphery of a process tube 1. In order to dispose a wafer 4 in the tube 1, a boat 5 in which the wafer 4 is, for example, disposed in a horizontal state and a plurality of the wafers 4 are supported longitudinally can be loaded or unloaded. The tube 1 is formed of an opaque quartz tube. Thus, its optical transmittivity is reduced as compared with its initial state as compared with a transparent tube, but the variation in the transmittivity is reduced even by the form formed on the tube 1 itself by the process since the transmittivity is reduced as compared with the initial state. Accordingly, even if the variation in the thickness of the film occurs by the process, the attenuation of radiation heat energy introduced into the tube 1 is reduced. Thus, the setting of the processing temperature can be facilitated.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a vapor phase growth furnace.

(Prior Art) In a vapor phase growth apparatus, for example, semiconductor wafers are arranged in a process tube and placed around the process tube.
At the same time, the process temperature is set by a controller, a process gas is introduced into the process tube, and each insertion/removal hole is formed on the wafer by vapor phase growth.

Here, the process tube is suitably made of a material that has good heat resistance and releases less contamination at high temperatures, and quartz glass is generally used.

Furthermore, the thermal energy from the heater into the process tube is transferred as radiant heat, especially under reduced pressure.
A transparent quartz tube is used to efficiently transfer radiant heat.

(Problems to be Solved by the Invention) In this type of vapor phase growth apparatus, there is a requirement to maintain a constant process temperature in order to form a film on an object to be processed, and the temperature is usually controlled by a thermocouple before the process starts. After the temperature is measured and stabilized at a predetermined process temperature, a process gas is introduced to perform vapor phase growth.

Here, in the process of forming a thin film such as a polysilicon film, a silicide film, or an insulating film on a wafer, the same type of film is inevitably formed on the inner surface of the process tube.

For this reason, the light transmittance of the process tube changes and the heat transfer efficiency of radiant heat decreases, so conventionally, the heater temperature setting was increased for each process based on experience, and the temperature was adjusted to maintain a constant process temperature. However, the temperature adjustment work was extremely complicated.

Note that depending on the degree of film formation on the process tube, the attenuation of radiant heat energy may reach a saturated state, but the process tube must be cleaned regularly, and after cleaning, the temperature settings should be adjusted again for each process based on experience. There was a need.

Therefore, an object of the present invention is to solve the two problems of the conventional technology, and to easily set the process temperature even if a film is formed on the inner surface of the process tube due to the process. The purpose of the present invention is to provide a vapor phase growth furnace.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a vapor phase growth furnace for vapor phase growth processing of a target object under heating in a process tube having a heating device around the tube. The process tube structure has a light transmittance that prevents a considerable portion of the attenuation of radiant heat energy caused by the film formed on the tube from being transmitted as radiant heat energy from the beginning.

(Function) In a conventional transparent process tube, the light transmittance gradually decreases due to the formation of a film on the process tube during the process. Therefore, the radiant heat energy injected into the process tube from the surrounding heating device is reduced as shown in Figure 1. As shown by the chain line, it changes depending on the film thickness, and the change is particularly rapid near the point where the film starts to form from a state of high transparency.

The attenuation of such radiant heat energy becomes more gradual as the film thickness increases.

Therefore, in the present invention, a considerable portion of the attenuation of radiant heat energy due to the film formed on the tube itself is reduced, for example, to an energy value closer to saturation than the maximum energy value d in Figure 1 (broken line C in the figure). From the beginning, the process tube structure has a light transmittance that does not transmit the amount of attenuation as radiant heat energy.

As a result, if such an opaque process tube is used, the radiant heat energy will be attenuated due to changes in light transmittance due to film formation on the tube, but this attenuation will be as shown by the solid line a in Figure 1. , changes due to the size of the film thickness are extremely small, and the influence on temperature control can be almost ignored, making temperature control much simpler than before.

(Example) Hereinafter, an example in which the present invention is applied to a vertical CVD furnace will be described with reference to the drawings.

A process gas can be introduced into the vertical process tube 1 from, for example, a gas inlet port 1a at its upper end. In order to support the lower end of the vertical process tube 1, a manifold 3 made of quartz glass is arranged, and the process tube 1 can be vertically supported via an O-ring 2.

This manifold 3 has an exhaust pipe 8 connected to its circumferential surface,
Evacuation and gas exhaust are possible.

Further, a heating device 6 is provided around the process tube 1.
The heating device 6 is comprised of a resistance heater, an infrared lamp, or the like.

In order to arrange the wafers 4 in the process tube 1, a boat 5 in which, for example, a plurality of wafers 4 are horizontally arranged and supported at a predetermined pitch in the vertical direction is loaded and unloaded. In order to position the boat 5 in the furnace core of the process tube 1, the boat 5 can be mounted on the heat insulating cylinder 7. And, this heat insulation tube 7 is
The boat 5 can be moved up and down by the loader device, and the boat 5 can be rotated during the process. Furthermore, this heat insulating tube 7 is tied to a cap member 9 that can be raised and lowered by a loader device (not shown), and this cap member 9 contacts the lower end flange 3a of the manifold 3 via the O ring 10 at its top dead center. The open end of the manifold 3 can be sealed.

Here, as a characteristic configuration of this embodiment, the process tube 1 is composed of an opaque quartz tube.9 Normally, the process tube is made of transparent quartz, but it is finished with sandblasting or opaque quartz (semi-transparent quartz). ) can be used.

Next, the effect will be explained.

When performing vapor phase growth processing, first set the boat 5 carrying the wafer 4 on the heat insulating cylinder 7! 7. The cap member 9 is raised by a loader device (not shown), and the cap member 9 moves to the top dead center where it seals the lower end flange 3a of the manifold 3 via the O-ring 10, and then stops [At this time, the boat 5 It will be set at the core position of the process tube 1.

Next, the inside of the process tube 1 is purged by introducing an inert gas through the gas introduction pipe 1a and exhausting the gas through the exhaust v8, thereby removing unnecessary air and the like.

After this purge operation is completed, the process temperature inside the process tube 1 is set by the heating device 6, and when the process temperature is stabilized at a constant temperature, a process gas is introduced from the gas introduction pipe 1a to perform a vapor phase growth process. There is.

At this time, the thermal energy emitted from the heating device 6 is transferred into the process tube 1 as radiant heat.

In this embodiment, the process tube 1 is composed of an opaque tube, so compared to a conventional transparent tube, the light transmittance is lower than the initial value; As a result, the change in transmittance due to the film formed on the tube 1 itself through the process is reduced compared to the conventional method.

Therefore, as shown by the solid line a in FIG. 1, the attenuation of the radiant heat energy injected into the tube 1 is reduced even when the film thickness changes due to the process. Comparing this with the case of conventional transparent process tubes, we can see that since conventional tubes are initially completely transparent, their light transmittance is high, and the initial radiant heat energy injected into the process tube is It is large as shown in illustration d of the figure. However, by repeating the process, a film is formed on the tube, so when the film starts to form, this light transmittance decreases to the affected area, and as the film of a certain thickness is formed, the attenuation amount increases. is saturated.

Therefore, in the process where a film starts to form, it is necessary to control the heater to raise the temperature by experience in order to keep the process temperature constant each time, and this work is extremely complicated.

In this embodiment, in particular, by configuring the opaque process tube 1 so that the portion corresponding to the initial large attenuation of radiant heat energy when using a transparent process tube is not transmitted from the beginning, this can be achieved. This makes it possible to prevent significant attenuation, and to reduce the amount of radiant heat energy that attenuates with film thickness, as shown by the solid line a in Figure 1, so the fluctuations in process temperature caused by this small attenuation can be almost ignored. This eliminates the need for temperature control that relies on experience as in the past.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible within the scope of the invention.

For example, in order to create a process tube structure with a light transmittance that does not transmit a considerable portion of the attenuation of radiant heat energy due to the film formed on the tube itself as radiant heat energy, it is necessary to For example, the process tube may be formed by blasting the surface after manufacturing the transparent process tube, or by constructing the process tube from an opaque material such as black SiC. Alternatively, Si may be placed around the transparent process tube 1.
It is also possible to form an opaque material such as C or the like.

Further, the present invention is not necessarily applied to vertical furnaces, but can be applied to horizontal furnaces as well, and furthermore, the present invention can be applied to various vapor phase growth furnaces that form films on objects to be processed in process tubes. be able to.

[Effects of the Invention] As explained above, according to the present invention, by using a process tube with lower light transmittance than a transparent tube, radiant heat energy generated by forming a film on a conventional transparent process tube can be reduced. Since it is possible to prevent a considerable portion of the attenuation from passing through from the beginning, even if a film is formed during the process, the attenuation of radiant heat energy is significantly reduced compared to conventional methods, and the effect on the process temperature setting is sufficiently reduced. , temperature setting can be achieved extremely easily.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram illustrating the relationship between the radiant heat energy injected into the tube and the film thickness formed on the duplex when the process tube of the present invention and the conventional process tube are used. , is a schematic explanatory diagram for explaining an embodiment in which the present invention is applied to vertical CVD. 1...Process tube, 4...Object to be processed, 6...Heating device. Agent Patent attorney Inoue - (1 other person) Figure 1 Figure 2

Claims (1)

[Claims] In a vapor phase growth furnace that processes an object to be processed by vapor phase growth under heating in a process tube having a heating device around it, attenuation of radiant heat energy due to a film formed on the tube itself. A vapor phase growth reactor characterized in that a considerable portion of the volume of the reactor has a process tube structure that has a light transmittance that does not transmit radiant heat energy from the beginning.