JPH0620980A - Vertical heat treatment furnace - Google Patents

Abstract

PURPOSE:To improve a flow of gas and enhance uniformity within the surface in a film thickness to be formed in a semiconductor wafer. CONSTITUTION:This embodiment is a vertical heat treatment furnace and is provided with an inner pipe 5b which has a plurality of gas guide holes 9 in a head part and a plurality of gas discharge holes 10 downwardly, and an outer pipe 5a which envelops the upper side of this inner pipe 5b and which has a gas guide pipe 7 downwardly. This reaction pipe has such a structure that comprises a enclosure chamber 5c which encloses a wall part 5d forming the gas discharge holes 10 of the inner pipe 5b and which has a gas discharge pipe 8, and gas supplied from the gas guide pipe 7 passes through the gas guide holes 9 and flows downwardly and comes into contact with the surface of wafers 1 arranged in parallel to each other and received within the inner pipe 5b, while gas flows in the radial direction and passes through the gas discharge holes 10 to discharge from the gas discharge pipe 8 to outside the pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment furnace for oxidizing and diffusing a wafer which is a semiconductor substrate used in a semiconductor element manufacturing process, and more particularly to a vertical heat treatment furnace in which reaction tubes are arranged vertically.

[0002]

2. Description of the Related Art FIGS. 2A and 2B are a longitudinal sectional view and a lateral sectional view showing an example of a conventional vertical heat treatment furnace. Conventionally,
In this type of heat treatment furnace, as shown in FIG. 2, a vertical boat 2 in which a plurality of wafers 1 are horizontally arranged and stored, a vertical boat 2 and a heat insulation and heat insulation tower 3 in which the vertical boat 2 is mounted. And an inner pipe 11b having a gas introduction hole 9 in the upper part and a gas discharge port pipe 8 in the lower part, and the inner pipe 11b.
An outer tube 11a that surrounds the reaction chamber 11 and forms a reaction chamber 11,
And a boat vertical drive mechanism 4 for loading / unloading the vertical boat 2 into / from the reaction tube 11 and opening / closing the opening of the reaction tube 11. Further, the reaction tube 11 is kept at a medium to high temperature of about 600 to 1200 ° C. by the heater 6.

Next, the operation of this vertical heat treatment furnace will be described. First, the vertical boat 2 loaded with the wafers 1 is lifted by the boat vertical drive mechanism 4 and slowly inserted into the inner tube 11b of the reaction tube 11 kept in a constant atmosphere by the reaction gas. Next, when the vertical boat 2 is raised to the upper limit and the insertion into the reaction tube 11 is completed, the processes such as the oxidation / diffusion of the wafer 1 are started.

The processing such as oxidation and diffusion is carried out by continuously repeating the following series of device operations for a certain period of time. First, the reaction gas introduced from the gas introduction pipe 7 at the bottom of the outer pipe 11a rises toward the head of the reaction pipe 11 between the outer reaction pipe 11a and the inner reaction pipe 11b.
The outer tube 11 of the reaction tube is heated by the heater 6.
The reaction gas that has risen between a and the inner pipe 11b is
The wafers 1 loaded on the vertical boat 2 are oxidized / diffused by being rectified and flowing evenly into the reaction tube 11 through a large number of gas introduction holes 9 in the head. Here, the reaction gas after the reaction and the surplus reaction gas are discharged from the gas discharge pipe 8.

After the series of operations of the apparatus are repeatedly performed for a predetermined time, the vertical boat 2 on which the wafers 1 are loaded.
Is driven downward by the boat up-and-down drive mechanism 4 to descend, and the oxidation / diffusion step is completed.

[0006]

In this conventional vertical heat treatment furnace, the structure of the reaction tube has an inner / outer double structure only on the gas introduction side having the gas introduction tube, and only one gas discharge tube is the inner tube of the reaction tube. Since it has a single-layer structure directly attached to, the discharge of gas does not flow evenly over the horizontally held wafer surface,
Since the gas flows and is discharged only in one direction where the gas discharge tube is attached, the in-plane uniformity of the oxide film thickness of the wafer located near the bottom of the reaction tube when the reaction tube is inserted is near the reaction tube head. Tends to get worse. Further, in the conventional structure, the degree of influence of various conditions of gas discharge such as gas discharge pressure on the in-plane uniformity of the oxide film thickness of the wafer is high, and it takes a lot of man-hours and time to determine and evaluate the conditions for obtaining the optimum conditions. There was a problem. In order to keep constant the optimum conditions determined by the evaluation, it is necessary to constantly manage the gas discharge pressure, and this daily management is troublesome and often causes errors.

FIGS. 3A and 3B are views for explaining the in-plane uniformity of the wafer processed by the conventional vertical heat treatment. By the way, in the heat treatment furnace shown in FIG.
When kept at about 0 ° C and oxidizing the wafer using oxyhydrogen,
As shown in FIG. 3, the relationship between the structure of the reaction tube and the in-plane distribution of the oxide film thickness is shown by using isobaric lines (lines obtained by connecting the same film thickness points). Further, as shown by the straight line graph, the film thickness of the wafer was greatly varied between the right side and the left side. Thus, it is shown that the film thickness tends to be thicker as it is closer to the mounting position of the gas exhaust pipe, and thinner as it is farther from the mounting position of the gas exhaust pipe. Is high. An object of the present invention is to provide a vertical heat treatment furnace capable of improving the gas flow and uniformly processing the in-plane in order to solve these problems.

[0008]

A vertical heat treatment furnace of the present invention has a plurality of gas introduction holes in its head and a plurality of gas discharge holes in its lower side wall, and a plurality of semiconductor substrates are stacked side by side. It has an inner pipe for accommodating the boat, an outer pipe that wraps the upper part including the head of the inner pipe and has a gas introduction pipe attached to the lower side, and surrounds and closes the side wall of the inner pipe and has a gas exhaust pipe. It has an outside room.

[0009]

The present invention will be described below with reference to the present invention.

1 (a) and 1 (b) are a longitudinal sectional view and a lateral sectional view showing an embodiment of the vertical heat treatment furnace of the present invention.
In this vertical heat treatment furnace, as shown in FIG. 1, the structure of the reaction tube 5 has a plurality of wall portions 5d below the inner tube 5b having a plurality of gas introduction holes 9 for introducing gas into the top wall portion. Gas discharge hole 10
And the surrounding chamber 5c having the gas discharge hole 10 and
This is the structure in which the gas exhaust pipe 8 attached to the outer chamber 5c is provided. Further, the gas introduction pipe 7 attached to the lower side of the outer pipe 5a of the reaction pipe is, as shown in FIG. 1B, a lower portion of the outer pipe 5a so as to extend in the radial direction with respect to the two gas discharge pipes 8. And is separated from the outer chamber 5c by an inner wall.

Next, the processing operation in the case of using the vertical heat treatment furnace of the present invention will be described while explaining the mutual relation and function of each part. First, the wafers 1 are loaded horizontally and in parallel in the vertical boat 2. Next, the vertical boat 2 is mounted on the heat insulation and heat insulation tower 3, and the heat insulation and heat insulation tower 3 is mounted on the boat vertical drive mechanism 4 and inserted into the inner pipe 5b. Next, when the vertical boat 2 is raised to the upper limit and the insertion into the reaction tube 5 is completed, the processing such as oxidation / diffusion of the wafer 1 is started.

The oxidation / diffusion process is carried out by continuously repeating the following series of device operations for a certain period of time. That is, first, the reaction gas introduced from the gas introduction pipe 7 at the bottom of the outer pipe 5 a of the reaction pipe 5 is
It passes between a and the inner tube 5b and rises toward the head of the reaction tube 5. Then, the reaction gas heated between the outer pipe 5a and the upper part of the inner pipe 5b while being heated by the heater 6 is dispersed and rectified in the inner pipe 5b by passing through a large number of gas introduction holes 9 at the head of the inner pipe 5b. And flows uniformly into the tube 5b. As a result, the wafers 1 loaded on the vertical boat 2 are oxidized and diffused. The post-reaction gas and the surplus reaction gas are uniformly sucked through a large number of gas discharge holes 10 radially formed in the wall portion 5d of the inner tube 5b in the lower stage of the reaction tube. The sucked reaction gas and surplus reaction gas radially and uniformly flow in the radial direction of the wafer 1, pass through the gas discharge holes 10, and are connected to the lower chamber outer chamber 5c of the two gas discharge pipes 8 Is discharged to the outside of the reaction tube 5.

After the series of operations of the apparatus are repeatedly performed for a predetermined time, the vertical boat 2 on which the wafer 1 is loaded.
Is driven downward by the boat up-and-down drive mechanism 4 to descend, and the oxidation / diffusion step is completed. Here, in this embodiment, the number of the gas discharge pipes 8 for discharging the reaction gas is two, but as another embodiment, the gas discharge pipes 8 are 3 for the purpose of making the discharge of the gas more uniform. An example in which a book or four books is used can be considered.

[0014]

As described above, the vertical heat treatment furnace of the present invention has an inner pipe having a plurality of gas introduction holes in the head and a plurality of gas discharge holes in the lower side, and the head of the inner pipe. A reaction tube having a structure in which an outer tube that wraps the side and has a gas introduction tube on the lower side, and an outer chamber that wraps the wall portion of the inner tube having the gas discharge hole and that has a plurality of gas discharge tubes is provided, The flow of gas supplied from the gas introduction pipe is made to flow radially through the gas introduction hole of the head of the inner pipe while uniformly contacting the wafer surface in the inner pipe, By discharging the gas from the outside through the gas discharge pipe through the gas discharge hole, there is an effect that a uniform film thickness can be formed in-plane on the wafer which is the semiconductor substrate accommodated in the reaction pipe. Also, as a secondary effect, the degree of influence of various conditions such as the gas discharge pressure on the in-plane uniformity of the oxide film thickness of the wafer is reduced, and it has been spent on condition determination evaluation and daily management for optimizing the various conditions. This has the effect of significantly reducing man-hours and time.

[Brief description of drawings]

FIG. 1 shows an example of a vertical heat treatment furnace of the present invention.

FIG. 2 is a vertical sectional view and a horizontal sectional view showing an example of a conventional vertical heat treatment furnace.

FIG. 3 is a diagram illustrating uniformity within a wafer surface processed in a conventional vertical heat treatment furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer 2 Vertical boat 3 Insulating heat insulation tower 4 Boat vertical drive mechanism 5,11 Reaction tube 5a, 11a Outer tube 5b, 11b Inner tube 5c Outer chamber 5d Wall part 6 Heater 7 Gas introduction tube 8 Gas exhaust tube 9 Gas introduction Hole 10 gas discharge hole

Claims (1)

[Claims] 1. An inner pipe for accommodating a boat having a plurality of gas introduction holes in a head portion, a plurality of gas discharge holes in a lower side wall, and a plurality of semiconductor substrates arranged side by side, and a head of the inner pipe. A vertical type that is provided with an outer tube that encloses an upper part including a portion and a gas introduction tube is attached to the lower side, and an outer chamber that surrounds and closes a side wall of the inner tube and that has a gas exhaust pipe. Heat treatment furnace.