JPS6329405B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to epitaxial growth devices.

Epitaxial growth devices can be classified into vertical and horizontal types. Horizontal epitaxial growth devices have the disadvantage of large variations in resistivity and thickness of the epitaxial layers that are formed due to the small number of sheets that can be processed, but on the other hand, since they do not have a rotation mechanism, it is easy to seal the reaction tube. It has the advantage of being easy to maintain as it does not change much over time, and is still widely used today.

On the other hand, the vertical epitaxial growth apparatus, unlike the above-mentioned horizontal type, has the advantage of being able to place a large number of silicon wafers on a rotating pancake-type susceptor or barrel-type susceptor, and also being able to precisely control the characteristics of the epitaxial layer. However, hermetic sealing of the rotating parts is important, and if not carefully maintained, the potential gas used for epitaxial growth can easily leak out and cause an explosion.

The present invention has been made in view of the advantages and disadvantages of both, and is intended to realize an epitaxial growth device that takes advantage of the advantages of both.One embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6. do.

As shown in FIG. 1, the epitaxial growth apparatus according to the present invention includes a reaction tube 1, a high-frequency heating coil 2, a wafer mounting table 3, a plurality of gas inlets 4...4,
and a gas exhaust port 5.

The reaction tube 1 is of an upright type, that is, of a vertical type, and the epitaxial growth process is performed after its end is hermetically sealed with a support 6.

The high frequency heating coil 2 is arranged adjacent to the outside of the reaction tube 1, and heats the wafer mounting table 3 to a predetermined temperature as is well known.

As is clear from FIG. 1, the wafer mounting table 3 is formed by stacking a large number of disk-shaped susceptors 31 in a vertical direction at regular intervals. Each susceptor 31 is formed of graphite with a thickness of 3 to 7 mm so as to be heated by induction by the high-frequency heating coil 2, and a single large-diameter wafer 32 is placed approximately in the center thereof. Therefore, the susceptor 31 is selected depending on the size of the wafer 32 to be placed, and for example, a wafer 32 with a diameter of 76 mm is selected.
Here, a susceptor 31 with a diameter of 80 mm is used. Further, the spacing between the susceptors 31 is approximately 10 mm from the lower surface of each susceptor 31 to the lower surface of the next, and the susceptors 31 are stacked in approximately 20 stages to increase the processing capacity. Furthermore, each susceptor 31 is fixedly integrated with three spacing rods 33 as shown in FIG. 1, and as shown in FIG. A bayonet-shaped screw hole 71 is provided in the fixing table 7 of the mounting table 3 at a position corresponding to the protrusion 34, and the wafer mounting table 3 is fixed on the fixing table 7 by both of them.

The most distinctive feature of the present invention is the plurality of gas inlets 4...4. The gas inlets 4...4 are arranged so as to surround the wafer mounting table 3 at equal intervals as shown in FIGS. 1 and 2, and extend vertically from the support table 6 to a height approximately equal to the height of the wafer mounting table 3. A tube wafer mounting table 3 formed of a tube.
A large number of gas ejection holes 41...41 are provided on the surface facing the. As is clear from FIG. 6, the gas ejection holes 41 are formed to correspond to the height of each susceptor 31 of the wafer mounting table 3.
The gas from 1 causes epitaxial growth only on the wafer 32 on the corresponding susceptor 31.

Distribution valves 10...10 are attached to these gas inlet ports 4...4, respectively, as shown in FIG.
3 into the doping tube 14 is successively and intermittently supplied into the reaction tube 1 by distribution valves 10...10. A solenoid valve is used as each distribution valve 10...10, and each distribution valve 10...10 is sequentially opened and closed in chronological order by a control circuit 15 such as a stepping relay. Specifically, gas inlet 4...
...4 is selected to rotate 8 to 10 times per minute, depending on the number of valves 10...10, so each distribution valve 10...10 is set to open and close sequentially every 0.5 seconds to 4.0 seconds. However, when the epitaxial layer to be formed is as thin as 2 to 5 .mu.m, this time sequence is made shorter to reduce variations; on the other hand, when the epitaxial layer is as thick as 50 to 100 .mu.m, even if it is made longer, there is not much effect.

The gas outlet 5 is connected to the support base 6 similarly to the gas inlet 4.
The wafer mounting table 3 is formed of a tube that extends vertically from the wafer mounting table 3 to a height substantially equal to the height of the wafer mounting table 3.
A large number of gas exhaust holes 51 are provided corresponding to the height of each susceptor 31. In FIG. 1, only two gas exhaust ports 5 are provided, but as shown in FIG.
... 5 so as to surround the wafer mounting table 3, and the gas inlet 4 and the gas outlet 5 are substantially opposed to each other to maintain a constant gas flow, thereby reducing variations in the epitaxial layer. Further, in order to efficiently exhaust the gas, as shown in FIGS. 2 and 6, recovery guide pipes 52 are provided at each gas exhaust port to make the gas flow uniform, thereby further reducing variations.

Further, as shown in FIG.
By providing a pore 43 of mmφ to introduce gas from the inner tube 42, the pressure of the gas ejected from the inner tube 42 into the tube is averaged, and the flow rate from each gas ejection hole 41 can be made constant and variations can be reduced.

As mentioned above, the epitaxial growth apparatus according to the present invention is characterized by having no rotating parts at all despite its vertical structure, and is also characterized in that it has no rotating parts at all in spite of its vertical structure. By supplying gas, the flow of gas is rotated, and an effect equivalent to that of rotating the wafer mounting table 3 is obtained.

Next, the mode of use of the epitaxial growth apparatus of the present invention will be explained.

First, the wafer mounting table 3 was removed from the fixing table 7.
Then, the wafers are simultaneously transferred from a jig having the same pitch as each susceptor 31 on the wafer mounting table 3, and the wafers are placed on each susceptor 31 on the wafer mounting table 3. Thereafter, the wafer mounting table 3 is fixed on the fixing table 7, and the reaction tube 1 and the support table 6 are sealed. Next, inert N ₂ gas is introduced into the reaction tube 1 through the gas inlet 4 for purging, the wafer mounting table 3 is heated to a predetermined temperature by the high-frequency heating coil 2, and a silicon source is introduced into the reaction tube 1 through the gas inlet 4. Dichlorosilane (SiH ₂ Cl ₂ ), H ₂ gas as a diluent gas, phosphine (PH ₃ ) as a dopant, etc. are introduced into the reaction tube 1 through distribution valves 10 . . . 10 for epitaxial growth. After epitaxial growth, it is returned to the reaction tube 1.
After introducing N ₂ gas, the reaction tube 1 is opened, the wafer mounting table 3 is removed from the fixing table 7, and the wafers on the wafer mounting table 3 are simultaneously collected into the aforementioned jig.

Further, according to the present invention, the gas path can be shortened to approximately the diameter of the susceptor, so that it has the advantage that uniform epitaxial growth can be performed at normal pressure. Therefore, compared to conventional epitaxial growth apparatuses which operated under reduced pressure, there is no need for a vacuum pump or the like, and maintenance of the epitaxial growth apparatus becomes easier.

As detailed above, the present invention provides numerous advantages. First, since it has no rotating parts, it is easy to seal airtight and maintenance is simple. Second, since the distribution valve rotates the gas flow, variations in the epitaxial layer can be reduced. Thirdly, since the wafer mounting table is not rotated, the number of wafers processed per unit volume can be increased, and the diameter of the reaction tube can also be reduced, so the high frequency oscillation output can be reduced. Fourth, since the gas flow can be formed short for each susceptor, the conversion rate to silicon is very good. Finally, it is easy to increase the diameter of the wafer.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional perspective view illustrating the epitaxial growth apparatus of the present invention, FIG. 2 is a top view illustrating the arrangement of the gas inlet and gas outlet of the epitaxial growth apparatus of the present invention, and FIG. FIG. 4 is a perspective view illustrating the wafer mounting table of the epitaxial growth apparatus of the present invention, and FIG. 5 is a process diagram illustrating the gas flow of the epitaxial growth apparatus of the present invention. FIG. 6 is a partially sectional perspective view illustrating the gas inlet, and FIG. 6 is a sectional view illustrating the flow of gas in the epitaxial growth apparatus of the present invention. Explanation of the main figure numbers: 1 is a reaction tube, 2 is a high-frequency heating coil, 3 is a wafer mounting table, 4 is a gas inlet, 5 is a gas exhaust port, and 6 is a support stand.

Claims (1)

[Scope of Claims] 1. A wafer mounting table formed by stacking an upright reaction tube and a disk-shaped susceptor that is heated by high-frequency induction and heated by high-frequency induction provided approximately at the center of the reaction tube in multiple stages with intervals, and surrounding the mounting table. The method includes a plurality of gas inlet ports and a gas exhaust port arranged in the same manner, and a distribution valve is provided for each of the gas inlet ports, and the gas is introduced in time series by opening and closing the distribution valves at approximately regular intervals. . An epitaxial growth apparatus characterized in that gas is intermittently supplied to the gas inlet. 2. The epitaxial growth apparatus according to claim 1, wherein the gas inlets are arranged at regular intervals and a gas outlet is arranged between the gas inlets. 3. In claim 1, the above-mentioned mounting table is arranged on a base provided on the lower surface of the reaction tube, and is detachably fixed from the base, and after the completion of epitaxial growth, the above-mentioned mounting stand is completely removed. An epitaxial growth device characterized in that it can be taken out of the reaction tube. 4. The epitaxy according to claim 1, wherein the gas inlet is formed in a tubular shape, and gas ejection holes are provided in the tube corresponding to the height of each susceptor of the mounting table. Yaru growth equipment. 5. The epitaxial growth device according to claim 5, characterized in that an inner tube is provided at the gas introduction port, and a large number of pores are provided in the inner tube to equalize the ejection pressure from the gas ejection hole. . 6. The epitaxy according to claim 1, wherein the gas outlet is formed in a tubular shape, and the gas outlet is provided in the tube corresponding to the height of each susceptor of the mounting table. Yaru growth equipment.