JPH0316208A - Apparatus for silicon epitaxial growth - Google Patents

Abstract

PURPOSE:To reduce the amount of unnecessary reaction product deposited on a reaction tube at the same time as film formation by a method wherein in addition to nozzle tubes for supplying reactive gas containing growing gas, nozzle tubes for supplying etching gas such as HCl in a direction avoiding a grown substrate crystal surface are provided. CONSTITUTION:A plurality of nozzle tubes comprise first nozzle tubes 10, 11 for supplying reaction gas containing silane growing gas to a grown surface and second nozzle tubes for supplying etching gas such as HCl in a direction avoiding the grown surface. Thus growing gas is supplied onto the grown surface of a substrate 1 as well as etching gas is supplied to a direction avoiding the grown surface of the substrate. Thus reaction product deposited on the wall of a reaction tube 2 can be prevented by etching function without influencing epitaxial growth on the substrate 1 surface and at the same time as film formation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vapor phase growth apparatus, and more particularly to a hot wall silicon ebitaxial growth apparatus in which a reaction vessel is vertically erected. [Prior Art] Ebitaxial growth technology has already become an important technical field in semiconductor manufacturing processes, and has become an essential process for device manufacturing, especially for bibolar devices. Furthermore, in recent years, demands for ultra-high integration and ultra-high speed devices have led to the development of high-speed Bi-CM devices with low power consumption.
SRAMs with an OS structure and DRAMs with an shrimp structure are being actively developed as a countermeasure against latch-up due to ultra-high integration, but all of these devices require an epitaxial process. ing.
In addition, in order to reduce the manufacturing process cost per device chip, efforts are being made to increase the throughput of silicon wafers and increase the number of wafers processed per batch in manufacturing equipment. Even in the case of epitaxial growth equipment, conventional barrel-type and pancake-type equipment
It has already become difficult to meet current requirements in terms of throughput, and recently various new types of equipment have been prototyped. For example, JP-A-63-008 was developed as a device capable of processing large quantities of large-diameter 6-inch wafers using a hot wall method using a vertical reaction tube.
It is proposed in No. 6424. Figure 5(a). (b
) shows an outline of this device. In the figure, single-crystal substrates 5 are held in a double-walled reaction tube consisting of an outer tube 1 and an inner tube 2, stacked horizontally at a certain interval on a substrate holder 4, and heated to 900° C. under reduced pressure.
The surface of the substrate 5 is heated to about 1200°C and silane gas such as dichlorosilane (SiH2CQ2), hydrogen
H1> and doping gas were introduced through the nozzle tube group 7 to cause epitaxial growth. 3 is a frame, 6 is a resistance heating furnace, 8 is a gas exhaust hole, and 9 is an exhaust port. The reaction tube has a double structure, with an outer tube 1 maintaining vacuum and a nozzle group 7 supplying reaction gas to a rotating single crystal substrate 5. The reaction gas is discharged through a large number of gas discharge holes 8 provided in the cylindrical surface of the inner tube 2. [Problems to be Solved by the Invention] The conventional silicon epitaxial growth apparatus described above uses a hot wall method using a resistance heating furnace 6, so during film formation, the reaction tube is heated to approximately the same temperature as the substrate crystal. Ru. Therefore, at the same time as the film is formed on the substrate crystal, reaction products are deposited in the reaction tube.
Particles are generated during film deposition, loading or unloading of substrate crystals, and deteriorate the quality of the deposited film. In addition, dopants incorporated into reactants deposited in the reaction tube re-diffuse into the gas phase during film formation, increasing the dopant partial pressure in the gas phase, making it difficult to control the resistivity of the film. For this reason, conventionally, in order to obtain a defect-free film with controlled resistivity, deposits were deposited in a reaction tube by vapor phase etching with an etching gas such as HCQ or wet etching with an etching solution every time several batches were grown. A step was required to remove the reaction products. Although a batch type vapor phase growth apparatus using a resistance heating furnace 6 is expected to have a high throughput because it can process large I substrate crystals at one time, the above is the reason why no improvement in throughput has been seen in the past. ．． An object of the present invention is to provide a silicon epitaxial growth apparatus that solves the above problems. [Differences between the invention and the prior art] Compared to the conventional silicon epitaxial elongation apparatus described above, the elongation apparatus of the present invention greatly reduces the deposition of reaction products in the reaction tube, which was a problem with the conventional apparatus. In order to improve the device throughput by reducing the amount of growth, in addition to the nozzle tube group that supplies a reaction gas containing a silane-based growth gas onto the crystal plane of the substrate to be grown, a
The difference is that it has a nozzle tube group that supplies etching gas such as CQ. [Means for Solving the Problems] In order to achieve the above object, a silicon epitaxial growth apparatus according to the present invention is provided with a reaction tube having a double tube structure consisting of an outer tube and an inner tube, installed every other tube, A plurality of silicon single crystal substrates are held in the reaction tube so as to be stacked almost horizontally at predetermined intervals, and the plurality of silicon single crystal substrates are In a hot-wall type silicon epitaxial growth apparatus, in which the reaction gas is flowed almost horizontally onto each of the crystal substrates to be elongated, and a film is elongated on the growth surface by a vapor phase growth method, the plurality of nozzles are provided. A first tube supplies a reaction gas containing a silane-based growth gas onto the growth surface.
hydrochloric acid (H) in a direction avoiding the nozzle tube group and the growth surface.
A second nozzle tube group supplies a reactive gas containing an etching gas such as CQ). Further, in the silicon epitaxial growth apparatus according to the present invention, a nozzle tube belonging to the second nozzle tube group is also arranged between the outer tube and the inner tube. [Function] It will be described below that the silicon epitaxial growth apparatus of the present invention can significantly reduce the amount of reaction products deposited in the reaction tube. If the reaction products or substances deposited in the reaction tube are reduced, the frequency of reaction tube etching can be reduced without reducing the reaction tube etching frequency, and the device throughput can be greatly improved. In particular, in a system where the reaction rate is determined by the supply of the reactant gas, such as an evitaxial elongation in which a certain length is carried out at a high temperature, the flow characteristics of the reactant gas are r! j. It greatly affects WA. In other words, the reaction between the reaction gas and the substrate crystal occurs along the streamlines of the reaction gas, and almost no reaction occurs in other regions. for example,
When a reactive gas containing a silane-based growth gas is supplied on the silicon substrate surface, film formation occurs only in the region along the gas flow line, and when a reactive gas containing an etching gas is supplied, etching occurs in that region. . Therefore, if the etching gas is supplied onto the surface of the substrate to be grown and at the same time the etching gas is supplied in a direction avoiding the surface of the substrate to be grown, the reaction products that should be deposited on the reaction tube wall can be removed from the reaction products by forming a shrimp film on the substrate surface. It can be prevented by etching without affecting growth and simultaneously with film growth. [Example] Next, the present invention will be explained with reference to the drawings. (Implementation gI41) Figure 1 (a). (b) is a diagram showing Example 1 of the present invention. In the figure, the apparatus of the present invention includes a pedestal 3 for supporting the apparatus, a double tube oval reaction tube consisting of an outer tube 1 and an inner tube 2, a substrate holder 4 for holding a single crystal substrate 5, and a resistance heating The furnace 6 is composed of a group of nozzle tubes for supplying the reaction gas, and the reaction gas is ejected from the nozzle tube 10, passes through the gas exhaust hole 8 provided on the wall of the inner tube 2, and is exhausted from the exhaust port 9. ．． As shown in FIG. 1(b), the nozzle tube group includes a nozzle tube 10 and a nozzle tube 11 for supplying a reaction gas containing S i H 2 C Q 2 that mainly contributes to film formation.
and a second nozzle group consisting of a nozzle pipe 12 and a nozzle pipe 13 for supplying a reaction gas containing HCQ that mainly contributes to etching a reaction product. There is. The reaction gas ejection direction from each nozzle tube varies depending on the flow conductance of the reaction gas flow on the wafer surface, which is determined by the reaction tube diameter, wafer diameter, wafer weight loading interval, distance between the nozzle tube and wafer, etc. Now, we will discuss the case where the inner tube diameter is 250 m, the wafer diameter is 150 m, the wafer loading interval is 10+m+, and the distance between the nozzle tube center axis and the wafer center is 1151 m. In this case, as a result of examining the gas flow line by changing the gas ejection direction, it was found that if the angle between the gas ejection direction and a straight line passing through the center of the nozzle tube cross section and the wafer center is in the range of 0° to 30''. It has become clear that the gas flow line passes over the wafer growth surface, and does not pass over the wafer growth surface in other cases.Therefore, in this example, the gas flow line passes over the wafer growth surface. As shown above, the arrangement is such that the reaction gas is ejected from the nozzle pipe 10 at 0°, from the nozzle pipe 11 at 301°, and from the nozzle pipes 12 and 13 at 180°, that is, in the direction of the inner wall of the reaction tube. The gas exhaust hole 8 was provided only in the area of the inner tube wall facing the nozzle tube lP1180°.In this arrangement, rlcpA is performed by the first nozzle tube group (nozzle tube 10 and nozzle tube 11), and rlcpA is performed by the second nozzle tube group. Tube group (nozzle pipe 12
and the nozzle pipe 13) to prevent reaction product from forming on the reaction tube wall. At this time, since the gas exhaust hole is provided only on the side of the inner tube opposite to the nozzle tube, the etching gas ejected from the second nozzle tube group flows along the inner wall of the inner tube to the gas exhaust hole 8 opposite to the nozzle. This allows for efficient etching of a wide range of the inner wall of the inner tube. An example of growing a silicon epitaxial film according to this example will be described below. Fifty silicon single crystal substrates 5 with a diameter of 150 mm were set at 10-im intervals on a substrate holder 4, and rotated at a rotation speed of 5 revolutions per minute (5 rpm). The substrate holder 4 is rotated, and the temperature inside the reaction tube is raised to 1050°C by the resistance heating furnace 6.
It was set to °C. The reaction gas is supplied from the nozzle pipes 10 and 11 of the first nozzle pipe group at a rate of Hz 10Q/nin.
, S I H2 C Q2 200nQ/ISIn
, P H s about 2 iQ/min, and H2t from the second nozzle tube group nozzle tube 12 and nozzle tube 13, respectively.
OQ/nin, HC Q200nQ/1in. The degree of vacuum in the reaction tube was set to 10 tOrr, and an N-type silicon epitaxial film was grown by 5 μl on a P-type silicon single crystal substrate. As a result of repeating the above epitaxial growth process, a high-quality epitaxial film was obtained. For this purpose, conventional equipment required reaction tube cleaning every 5 batches, but with the device of the present invention, reaction tube cleaning frequency was reduced to 20.
It decreased with each batch. Moreover, in conventional equipment, dopant re-diffuses into the gas phase from the reaction products deposited on the reaction tube wall, so in order to control the resistivity, the pH and concentration in the reaction gas must be delicately controlled for each batch. However, with this device, there was almost no change in resistivity even when 20 consecutive batches of growth were performed with the P H s concentration kept constant, indicating that resistivity control could be easily performed. It was revealed. (Example 2) Figure 2 (a). (b) is a diagram showing Example 2 of the present invention. The second embodiment differs from the first embodiment in that the second nozzle tube group (16, 17) is provided on the opposite side of the first nozzle tube group (14, 15), that is, in the vicinity of the gas discharge hole 8. The structure is the same as Example 1 except for the nozzle tube arrangement. In this embodiment, the second nozzle tube group (16, 17) is connected to the gas exhaust hole 8.
Since the etching gas is easily discharged from these nozzle pipes, the influence of the etching gas on shrimp growth is further reduced than in the case of Example 1. Therefore, the SI required to obtain the same growth rate is
This has the advantage that the H2cQ2 flow rate can be lower than in the first embodiment. In the case of this embodiment, almost no etching gas is supplied to the region of the inner tube wall where no gas discharge hole is provided, but a certain length of gas supplied from the first nozzle tube group is ejected toward the wafer. ,
As a result, the growth gas is ejected in the direction of the gas exhaust hole, and the reaction products are deposited near the exhaust hole, so there are few problems caused by this.

(Example 3) Figure 3(a). (b) is a diagram showing Example 3 of the present invention. The third embodiment differs from the first embodiment in that one of the second nozzle tube groups (20, 21) is arranged to eject gas in a 45° direction. Example 1 except for the nozzle tube arrangement
is the same as In this embodiment, the nozzle tubes 20 of the second nozzle tube group (20, 21) oriented at 180° are used to etch the deposits on the reaction tube wall, and the nozzle tubes 21 oriented at 35° are used to etch the substrate holder. (Example 4) FIG. 4(a). (b) is a diagram showing Example 4 of the present invention. The fourth embodiment differs from the first embodiment in that one nozzle pipe 25 of the second nozzle pipe group (24, 25) is arranged between the inner pipe 2 and the outer pipe 1. The structure is the same as Example 1 except for the nozzle tube arrangement. This embodiment has the effect of preventing reaction substances from being deposited not only on the inner wall surface of the inner tube 2 but also on the inner wall surface of the outer tube 1. In normal shrimp growth, the amount of deposition on the outer tube wall is smaller than that on the inner tube wall, so the effect of this example is small, but it can be used to selectively increase shrimp growth or to steepen the dopant globules at the epi-substrate interface. The effect of this embodiment is significant under growth conditions where the reaction gas is not sufficiently decomposed within the inner tube, such as when growth is performed at low temperatures.

This actual koji example can also be carried out in combination with Example 2 and Example 3. Note that Examples 2 to 4 also apply to Example 1.
It was also effective in preventing deposits, and the frequency of reaction tube cleaning could be reduced.

〔Effect of the invention〕

As explained above, the silicon epitaxial growth apparatus of the present invention has a nozzle tube group that supplies a reaction gas containing a silane-based growth gas onto the crystal plane of the substrate to be grown, as well as a nozzle tube group that supplies a reaction gas containing a silane-based growth gas onto the crystal plane of the substrate to be grown. Since the reactor has a nozzle tube group that supplies etching gas such as HCQ to the reactor, it has the effect of greatly reducing the amount of unnecessary reaction products that accumulate in the reaction tube at the same time as the film is removed. As a result, the frequency of etching the reaction tube is reduced, which has the effect of improving the device throughput.

[Brief explanation of drawings]

FIG. 1 [a] is a vertical cross-sectional view showing a silicon epitaxial growth apparatus according to Example 1 of the present invention, and FIG.
2(a) is a vertical sectional view showing a silicon epitaxial growth apparatus according to Example 2 of the present invention, and FIG. ) of a-a'
4i is an enlarged view, FIG. 3(a) is an ltI cross-sectional view showing a silicon epitaxial growth apparatus according to Example 3 of the present invention, and FIG. 3(b) is a cross-sectional view taken along a-a' a of FIG. 3(a). An enlarged view, FIG. 4(a) is a longitudinal cross-sectional view showing a silicon epitaxial growth apparatus according to implementation S4 of the present invention, and FIG. 4(b) is an enlarged cross-sectional view taken along the line aa' of FIG. FIG. 5(a) is a vertical cross-sectional view showing a conventional silicon epitaxial growth apparatus, and FIG. 5(b) is an enlarged cross-sectional view taken along line aa' in FIG. 5(a). 1... Outer tube 2... Inner tube 3... Frame 4... Substrate holder 5... Single crystal substrate 6... Resistance heating furnace 7... Nozzle tube group
8... Gas exhaust hole 9... Exhaust port 10, 11, 14, 15. 20... Nozzle pipe (first nozzle pipe group) t2, 13, 16, 17, 21, 24. 2
5... Nozzle pipe (second nozzle pipe group) ε, blade 4 non-extrusion ((:L) Fig. 1 (b) Katsu 1 Fig. 5. Single crystal substrate (α) Fig. 2 ( (L) Fig. 3 (b) Fig. 2 (b) Fig. 3 (α) Fig. 4 (CL) Fig. 5 1. Gut tube (b) Fig. 4 4 (b) Fig. 5

Claims (2)

[Claims] (1) A reaction tube with a double tube structure consisting of an outer tube and an inner tube is installed vertically, and multiple silicon single crystal substrates are held in the reaction tube so as to be stacked almost horizontally at predetermined intervals. and flowing the reaction gas almost horizontally onto the growth surface of each of the plurality of silicon single crystal substrates from a plurality of nozzle pipes having a plurality of reaction gas discharge holes in the longitudinal direction,
In a hot wall type silicon epitaxial growth apparatus for growing a film on the growth surface by a vapor phase growth method,
The plurality of nozzle tubes include a first group of nozzle tubes that supplies a reaction gas containing a silane-based growth gas onto the growth surface, and an etching gas such as hydrochloric acid (HCl) in a direction that avoids the growth surface. a second nozzle tube group for supplying a reaction gas containing a silicon epitaxial growth apparatus. (2) A nozzle pipe belonging to the second nozzle pipe group is also arranged between the outer pipe and the inner pipe.
1) The silicon epitaxial growth apparatus described in item 1).