JPS60101935A - Apparatus for semiconductor heat treatment - Google Patents

Abstract

PURPOSE:To enable high-temperature heat treatment without causing crystalline defects, by constituting a reaction container for heat treatment with an L-shaped reaction container consisting of a vertical part with temperature gradient and a horizontal part with uniform temperature state, and moving an Si substrate positioned horizontally through the vertical part and then through the horizontal part so as to subject it to heat treatment therein. CONSTITUTION:An L-shaped annular furnace 6 is constituted with a horizontal part and a vertical part positioned on the inner end of the horizontal part. A similarly L-shaped reaction container 3 is housed within the furnace. An inlet 5 and an outlet 4 for atmosphere gas are provided, respectively on the ends of the horizontal and vertical parts of the container. A large diameter Si substrate 1 put on a carbon-made support table 2 is inserted into the vertical part having temperature gradient. The table 2 is further pushed up together with the substrate by means of an insert bar 7 to pass through a temperature gradient section. Thereafter, only the substrate 1 is moved with a horizontally moving bar 8 to the horizontal part having a uniform temperature state, where the substrate 1 is heat treated as required. The substrate 2 is then taken out from the apparatus in the reversed order of operations.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a semiconductor heat treatment apparatus, and in particular, in the process of increasing the temperature from room temperature to the heat treatment temperature, and/or in the process of decreasing the temperature from the heat treatment temperature to room temperature, crystal defects are removed. The present invention relates to a semiconductor heat treatment apparatus that prevents the occurrence of such occurrences.

[Background of the invention]

BACKGROUND ART The process of housing a semiconductor substrate in a high-temperature region and heat-treating it is one of the important processes in the manufacturing process of semiconductor devices such as LSIs, including, for example, impurity diffusion and oxide film formation.

A conventional heat treatment process will be explained using an example of a process for forming an oxide film on a silicon wafer. Figure 1 shows the cross-sectional structure of the oxide film forming furnace.
1 is a silicon wafer, and 2 is a silicon wafer mounting table made of, for example, quartz. On the silicon wafer mounting table 2, a large number of wafers 1 are arranged substantially vertically as shown in the figure. Also 3
1 is a reaction vessel made of quartz, one end of which is provided with an opening 4 for the insertion and removal of Ueno gas, and the other end provided with an atmospheric gas introduction hole 5. 6 is a commonly used annular resistance heating furnace with points A and B in the furnace.

The temperature distribution at points C and D is maintained as shown in FIG. When forming an oxide film on the silicon wafer 1, first, the heating furnace 6 is heated while N2,02 gas is introduced as an atmospheric gas into the reaction vessel 3, and the B-C region is brought to a desired temperature (for example, l100C±). IC). Next, the mounting table 2
A large number (30 to 50) of vertically set silicon wafers 1 are transferred to the B-C region and held until a desired oxide film is formed. In this case, the atmospheric gas may be changed to an atmosphere containing water vapor, if necessary.

After holding for a predetermined period of time, the silicon wafer IFi on which the oxide film has been formed is again taken out of the container 3 through the opening 4.

In the above process, the silicon wafer 1 is subjected to a thermal cycle from room temperature to high temperature (up to 1100 C), so that various crystal defects may occur. For example, if a large number of silicon wafers are inserted at once, heat transfer between silicon wafers or within the plane becomes uneven because the heat capacity of the inserted object is large. As a result, the temperature of the silicon wafer 1 is raised or lowered while the in-plane temperature is not restricted, and thermal stress dislocations occur within the plane of the silicon wafer. There is a method to prevent such problems, and a method is to move the silicone in and out of the high temperature area (B-0) very slowly (for example, at a speed of about 50 mm/min). Temperature gradient inside reaction vessel 3 (A-8
1) is large in the direction perpendicular to the silicon wafer surface, consideration must be given to achieving uniform heat transfer even to inserts with a large heat capacity by slowing down the feeding speed of the silicon wafer 1. For example, non-uniformity within the silicon wafer surface can be minimized (temperature differences between silicon wafers inevitably occur), and thermal stress dislocations can be prevented from occurring.

However, in recent years, as the diameter of semiconductor substrates has increased to 4 inches and 5 inches, the thickness has also tended to increase from 0.6 mm to 0.7 mm in order to prevent wafer damage. It is becoming impossible to prevent the problem of crystal defect generation.

In other words, in the conventional method, the wafer is mounted vertically in order to prevent temperature unevenness within the wafer surface that occurs when the silicon wafer is taken in and out of the reaction vessel, but with large diameter substrates, the weight increases due to the aforementioned increase in diameter and thickness. It was found that such a vertical mounting method causes a local concentration of load, and crystal defects are generated from that location.

As a solution to this new problem in heat treatment of large-diameter substrates, as shown in FIG. There is a method of slowly raising and lowering the temperature of 6 to a predetermined temperature. However, even if the load concentration on the spacer 7 is reduced compared to the conventional method, it is essentially impossible to reduce it to zero, and the problem of crystal defect generation cannot be solved.

Another disadvantage of this method is that it is difficult to supply a uniform gas, resulting in non-uniform thickness of the formed film.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor heat treatment apparatus that improves the problems of conventional apparatuses, prevents the occurrence of crystal defects, etc. even on large-diameter semiconductor substrates, and enables high-temperature heat treatment.

[Summary of the invention]

In order to achieve the above object, in the present invention, when a semiconductor substrate is inserted into/taken out from a high temperature region in a reaction vessel of a heat treatment apparatus, in a region having a temperature gradient,
The purpose of this method is to arrange and transport the semiconductor substrates so that the surfaces of the semiconductor substrates are perpendicular to the direction of gravity and the direction of the temperature gradient.

[Embodiments of the invention]

An embodiment of the present invention will be described based on FIGS. 4 to 6.

FIG. 4 shows a schematic configuration of an embodiment of a semiconductor heat treatment apparatus according to the present invention. In Figure 4,
1st. The same reference numerals are given to the same parts B as in the conventional apparatus in FIG. 5th
The figure shows the temperature distribution inside the reaction vessel 3. There is a temperature gradient from room temperature to the reaction temperature between area A and B on the opening 4 side of the reaction vessel, but the area between B and 0 is a uniform heating zone. An atmospheric gas inlet 5 is provided at one end of the reaction vessel 3 . A large-diameter (φ5 inch) silicone unit S10 is set horizontally on a quartz or SiC-coated carbon mounting table 2, and is fed from the container opening 4 to point B by an insertion rod 7. At this time, since the temperature gradient is large in the direction perpendicular to the silicon wafer surface,
Temperature non-uniformity within the wafer surface can be kept to a minimum by paying attention to the insertion speed from the standpoint of heat capacity. Further, since the silicon wafer 10 is inserted into the high temperature region in a horizontal state, the weight of the silicon wafer is not concentrated at one point. Therefore, the large diameter silicon wafer 10 can be inserted into a high temperature region without causing thermal stress dislocation. Next, it is transferred to the introduction hole 5 side in the uniform heating zone by the horizontal movement rod 8 and set at a predetermined position in the container. After several silicon wafers 10 have been stored in the same manner, atmospheric gas for forming an oxide film is introduced through the introduction hole 5, and heat treatment for forming an oxide film is performed for a desired time. After the formation of the predetermined oxide film 9 has been completed and the atmospheric gas has been changed, the silicon wafer 10 is taken out of the container 3 by the reverse operation of the insertion.

According to this example, even in a large-diameter semiconductor substrate, the in-plane temperature distribution of the substrate can be maintained uniformly and the substrate can be moved in and out of a high-temperature region, and the concentration of the chipped semiconductor load can be prevented and high rAA heat treatment can be performed. Furthermore, since the atmospheric gas is supplied uniformly, the occurrence of crystal defects can be prevented and a uniform oxide film can be formed.

Next, FIG. 6 shows an embodiment in which the present invention is applied to a continuous heat treatment apparatus. Openings 4 for loading and unloading wafers are provided at both ends of the reaction vessel 3 in the vertical direction and have a temperature gradient from room temperature to reaction temperature or from reaction temperature to room temperature. The silicon wafer 10 is inserted through one opening 4 and, after completing the formation of a desired oxide film while moving through the horizontal uniform heating zone 9, is continuously taken out from the other opening 4.

As explained above, according to this embodiment, it is possible to heat-treat a large-diameter semiconductor substrate with high work efficiency.

The semiconductor heat treatment apparatus R shown in FIG. 4 of the present invention
5000mm thick oxide film kl100 on 6-inch wafer
No slip lines (linear crystal defects caused by thermal stress dislocations) were observed when the film was formed using R.

Although the above embodiment describes heat treatment for forming an oxide film on a silicon wafer, the present invention can be applied to equipment having high-temperature heat treatment steps such as impurity diffusion, CVD film forming equipment, and epitaxial growth equipment.

〔Effect of the invention〕

According to the present invention, even large-diameter semiconductor substrates can be subjected to high-temperature heat treatment without causing crystal defects or the like.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a conventional semiconductor heat treatment apparatus.
FIG. 2 is a diagram showing the temperature distribution inside the reaction vessel in a conventional semiconductor heat treatment apparatus, FIG. 3 is a block diagram showing another example of the conventional semiconductor heat treatment apparatus, and FIG. 4 is a diagram showing a semiconductor heat treatment apparatus according to the present invention. FIG. 5 is a diagram showing the fan degree distribution in the reaction vessel in a semiconductor heat treatment apparatus according to the present invention, and FIG. 6 is a diagram showing an example in which the present invention is applied to a semiconductor continuous heat treatment apparatus. FIG. 1.1010. Semiconductor substrate, 2... mounting table, 3...
Reaction container, 4... Open [ ] part, 5... Atmosphere gas introduction hole, 6... Power 1] Heat furnace. Agent Patent Attorney Tatsuyuki Unuma Invited IJ Haku 2m No. 31 ¥l Haku 4 (2111

Claims (1)

[Claims] 1. A semiconductor heat treatment apparatus having a reaction vessel for performing high-temperature heat treatment on a semiconductor substrate, a heating means for forming a predetermined temperature gradient in the reaction vessel, and a transfer means for transferring the semiconductor substrate into and out of the reaction vessel, A semiconductor heat treatment apparatus characterized in that semiconductor substrates are arranged and transferred in a region having a temperature gradient in a container so that the surfaces of the semiconductor substrates are perpendicular to the direction of gravity and the direction of the temperature gradient.