JPH084075B2 - Vapor phase growth equipment - Google Patents

Description

The present invention relates to an apparatus for forming a vapor phase growth layer on the surface of a semiconductor wafer, and particularly for forming a vapor phase growth layer uniformly on a large number of semiconductor wafer surfaces. The present invention relates to a vapor phase growth apparatus.

[Conventional technology]

Vapor phase such as CVD method to form SiO ₂ film, nitride film, polycrystalline silicon film and epitaxial growth to form single crystal silicon film by using vapor phase chemical reaction on semiconductor wafer (hereinafter abbreviated as “wafer”) Growth technology is widely applied in the LSI manufacturing process.

In recent years, the wafer diameter has been increased (> 6 inches in diameter) for the purpose of reducing the process cost and improving the product yield, and the CVD apparatus has also been increased in size to meet such trends. Processing capacity is increasing.

On the other hand, along with the high integration and high speed of devices, there is also a demand for highly accurate uniformization of a thin film to be formed.

As shown in JP-A-59-50093 as a CVD apparatus that meets the above requirements, the wafers are arranged in a reaction container so that the main surfaces thereof are arranged at equal intervals and the wafers are substantially contained. Using the installed inner tube as a heating source to uniformly heat the wafer, and supplying a reaction gas between each wafer using a nozzle having holes, a uniform CVD film can be formed on a large number of wafers at one time. A new target CVD device has been proposed.

[Problems to be solved by the invention]

However, in the above-described conventional vapor phase growth apparatus, it is difficult to supply an equal amount of raw material gas to each wafer because the consideration of the flow rate distribution of the raw material gas supplied from each hole of the nozzle is insufficient. However, there is a problem that it is difficult to obtain highly accurate wafer-to-wafer film thickness uniformity. The main reason for this is that when the source gas is supplied from one end of the nozzle and the gas is ejected from a large number of holes arranged in the flow direction, the pressure in the nozzle pipe is distributed. As a solution to this, the nozzle tube diameter is made extremely large. There is a method of making the ejection hole outflow resistance smaller than the resistance in the nozzle pipe by making the diameter of the ejection hole extremely small so that the pressure in the nozzle pipe is substantially uniform in each part. However, the above-mentioned drawbacks are that the size of the inside of the furnace is limited, and the flow velocity of the gas ejected onto the wafer is increased, and the film thickness uniformity on the wafer surface is impaired.

An object of the present invention is to provide a vapor phase growth apparatus capable of relatively easily forming a uniform thin film between wafers even for a large number of large diameter wafers.

[Means for solving problems]

The above object is to connect a gas supply nozzle to a first chamber, which has a gas inlet at one end and has substantially the same chamber pressure in the gas flow direction, and to connect the first chamber to the first chamber. This is achieved by having a two-chamber structure having a second chamber having a pressure lower than that of the first chamber and having holes for supplying gas to the wafer in a direction different from the direction of gas flow from the chamber.

The holes can have various shapes such as a circle, an ellipse, an oval, and a rectangle.

[Action]

The outflow resistance of the outlet connecting the first chamber and the second chamber of the nozzle is made sufficiently larger than the outflow resistance in the first chamber,
By making the pressure distribution in the chamber substantially uniform,
The gas flow rate supplied from the chamber can be made uniform in each part of the second chamber. Further, the second chamber is provided with ejection holes (or slits) for obtaining the gas flow velocity that gives the best uniformity within each wafer surface in a direction different from the direction of the gas flow supplied from the first chamber. The source gas can be uniformly supplied to each wafer at an optimum flow rate.

〔Example〕

Hereinafter, the present invention will be described with reference to FIGS. 1 and 2 by using the epitaxial growth of Si as an example.

Reference numeral 1 denotes a silicon single crystal wafer, which is charged into a quartz holder 2 with two main surfaces each having 10 layers, and 20 wafers in total. The holder 2 is rotated by a motor 8 in order to improve the uniformity within the wafer surface. The wafer 1 is surrounded by a cylindrical carbon susceptor 4, and the high frequency coil 5 induction-heats the susceptor 4 to uniformly heat the wafer 1 to the epitaxial growth temperature. 6 is a nozzle for supplying the raw material gas,
As shown, it comprises a first chamber 6a and a second chamber 6b. 6c is a connecting pipe, and 6d is an ejection hole. Reference numeral 7 is an exhaust gas exhaust pipe. Three
Is a quartz bell jar serving as a reaction vessel.

Next, an example of epitaxial growth will be described.
First, two large-diameter wafers each having a diameter of 12.7 cm (5 inches) are superposed on each other, and 10 stages of 20 wafers are charged into the holder 2 at 1 cm intervals and rotated at 20 rpm. 40l / min hydrogen gas from nozzle 6
After supplying for 10 minutes to create a hydrogen atmosphere in the furnace, the high-frequency coil 5 is energized to raise the temperature of the susceptor 4 to 1150 ° C. The SiCl ₄ raw material is mixed in hydrogen gas in an amount of about 1.5 mol% to start epitaxial growth. At this time, a mixed gas of hydrogen and SiCl ₄ approx. 40 l / min
Is supplied to the first chamber 6a of the nozzle 6, and is supplied to the second chamber 6b through five connecting pipes 6c provided at equal intervals of 20 mm. The inner diameter of the first chamber 6a is 15 mm and the inner diameter of the connecting pipe 6a is 2 mm.
A substantially equal amount of raw material gas is supplied to the second chamber 6b from the book connecting pipe 6c. The second chamber 6b is provided with eleven ejection holes 6d having a diameter of 3 mm, which are shifted by 90 ° from the position of the connecting pipe 6c according to the distance between the loaded wafers, so that the raw material gas having a slower flow velocity than the flow velocity in the connecting pipe 6c is provided. It is uniformly supplied to each wafer 1. The exhaust gas is discharged to the outside of the bell jar 3 through the exhaust nozzle 7.

After performing epitaxial growth for a predetermined time, SiCl ₄
The supply of raw materials is stopped and the temperature drop of the susceptor 4 is started. When the wafer temperature becomes low, the bell jar 3 is opened and the wafer 1 is taken out.

As a result of forming the epitaxial layer with a thickness of 10 μm on 20 wafers with a diameter of 12.7 mm according to this embodiment, the film thickness variation between wafers ±
4% was obtained, and the uniformity could be more than doubled compared with the conventional variation (± 8.2%).

By the above operation, an epitaxial wafer having a uniform epitaxial film thickness between wafers can be obtained.

In this embodiment, the nozzle in which the connecting pipe has a hole shape has been described, but the same effect can be obtained if the connecting pipe has a slit shape with a sufficiently small gap.

FIG. 3 is a cross-sectional explanatory view of a nozzle in which the inside of one nozzle tube is divided into two chambers to obtain the same effect. Also,
FIG. 4 is a cross-sectional structural explanatory view of a nozzle in the case of forming a double tube to prevent the deposition of silicon in the nozzle tube and preventing the temperature rise of the nozzle 6 by the gas cooling passage 6e.

[Advantages of the Invention] As described above, according to the apparatus of the present invention, it is possible to easily form a thin film evenly on a large-diameter wafer between the wafers.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a vapor phase growth apparatus showing an embodiment of the present invention, FIG. 2 (a) is an enlarged view showing a nozzle used in the vapor phase growth apparatus of FIG. 2 (b) is a cross-sectional view taken along the line AA of FIG. 2 (a), FIG. 3 and FIG.
The drawing is a cross-sectional view showing a nozzle according to another embodiment. 1 ... Wafer, 2 ... Holder, 3 ... Belger, 4 ...
Susceptor, 5 ... Heating coil, 6 ... Gas nozzle, 6a ...
... 1st chamber, 6b ... 2nd chamber, 6C ... connecting pipe, 6d ... ejection hole, 7 ... exhaust nozzle, 8 ... motor.

Claims (2)

[Claims] 1. The semiconductor wafers have their principal surfaces parallel to each other,
A large number of the raw material gases are placed side by side in a reaction vessel, and the raw material gas is introduced from one end of a gas supply nozzle having a large number of holes installed in the reaction vessel while being heated, and the raw material gas is introduced substantially parallel to the main surface from the outer periphery of the semiconductor wafer. In the apparatus for supplying and forming a vapor phase growth layer, the gas supply nozzle has a gas supply port from the outside of the container, and the first chamber and the first chamber have substantially the same pressure in the longitudinal direction of the nozzle. And a second chamber having a hole for supplying a raw material gas to the surface of the semiconductor wafer and injecting gas from the second chamber to the semiconductor wafer from the first chamber to the second chamber. A vapor phase growth apparatus characterized in that the direction is different from the gas flow direction. 2. The method according to claim 1 above, wherein
The vapor phase growth apparatus, wherein the hole for supplying the gas from the chamber to the semiconductor wafer is any one of a circular hole, an elliptical hole, an oval hole, and a rectangular hole.