JP2778321B2 - Vapor phase silicon epitaxial growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase silicon epitaxial growth apparatus, and more particularly to a vapor phase silicon epitaxial growth apparatus in which a reaction vessel is vertically assembled.

[0002]

2. Description of the Related Art FIG. 5 is a longitudinal sectional view showing a conventional vapor phase silicon epitaxial growth apparatus. Hereinafter, JP-A-63
The present growth apparatus at -008424 will be described.
A silicon single crystal substrate 5 is held on a substrate holder 4 so as to be horizontally stacked at predetermined intervals, and heated to about 900 to 1200 ° C. using a resistance heating furnace 7 under reduced pressure, and a silane-based gas such as dichlorosilane is applied to the substrate surface. A mixed gas composed of a doping gas such as phosphine, an etching gas such as hydrogen chloride gas, and a carrier gas such as argon and nitrogen is supplied from a nozzle tube 8, and only a hydrogen gas is supplied from another nozzle tube 8. And epitaxial growth. The reaction vessel has a double structure held by a gantry 3 and holds a vacuum with an outer tube 1, and supplies a mixed gas and a hydrogen gas to a rotating single crystal substrate 5 using a plurality of nozzle tubes 8. The nozzle tube 8 has a plurality of gas discharge holes 12 at equal intervals and having the same diameter. Mixed gas and hydrogen gas
The gas is exhausted from the exhaust port 11 through a number of gas exhaust holes 10 provided in the cylindrical surface.

[0003]

In the above-mentioned conventional vapor phase silicon epitaxial growth apparatus, the doping gas such as phosphine is used for doping impurities into the epitaxial film grown on the single crystal substrate 5. The nozzle tube 8 through which the doping gas flows has a plurality of gas emission holes 12 for emitting the doping gas substantially in parallel to all the single crystal substrates 5.

[0004] Therefore, when doping an epitaxial film grown on a large number of single crystal substrates 5 by increasing the height of the reaction vessel, the nozzle tube 8 becomes long, and the doping gas is supplied to the gas discharge holes on the upstream side of the nozzle tube 8. Pressure loss occurs on the downstream side because the gas is discharged mainly from
Of doping gas released from the upstream side is smaller than that on the upstream side. As a result, among the plurality of single-crystal substrates 5, the resistivity of the epitaxial film is such that the upstream single-crystal substrate 5 has a higher doping gas flow rate and a larger dopant supply amount, and thus the upstream has a lower downstream resistivity. The phenomenon that becomes smaller than that of occurs. Therefore, when the number of single crystal substrates 5 to be grown is increased, there is a disadvantage that the uniformity of resistivity between the single crystal substrates 5 is significantly deteriorated.

Regarding the uniformity of the in-plane epitaxial film resistivity of the single-crystal substrate 5, the diffusion coefficient in the carrier gas does not match between the silane-based gas such as dichlorosilane and the doping gas such as phosphine, and the condition of the epitaxial growth controlled by the mass transport is limited. Therefore, even if the flow of the carrier gas or the silane-based gas is optimized to improve the uniformity of the in-plane epitaxial film thickness of the single crystal substrate 5, it is difficult to optimize the flow of the doping gas at the same time. is there. Therefore, there is a disadvantage that it is difficult to simultaneously improve the in-plane epitaxial film resistivity uniformity and the film thickness uniformity of the single crystal substrate 5.

[0006]

A vapor phase silicon epitaxial growth apparatus according to the present invention holds a plurality of vapor-grown silicon substrates so as to be horizontally stacked at a predetermined interval and has a plurality of gas discharge holes having a plurality of gas discharge holes. A high-concentration impurity is doped as a doping source for an epitaxial film in a vapor-phase silicon epitaxial growth apparatus in which an epitaxial film is vapor-phase-grown on each vapor-deposited surface of a plurality of vapor-deposited silicon substrates from an epitaxial growth nozzle tube. Having a single crystal substrate, which is mounted simultaneously with the vapor-deposited silicon substrate, and the upper and lower portions of the upper and lower portions of the vapor-deposited silicon substrate group or those obtained by vertically dividing the vapor-deposited silicon substrate group. For gas etching, which is located at the bottom and gas-etches only this doping source during epitaxial growth Provided with a nozzle tube, wherein the epitaxial growth nozzle tube has a structure without the epitaxial growth gas discharge holes of the doping source.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.

In this embodiment, a stand 3 for supporting the apparatus, a reaction tube having a double tube structure comprising an outer tube 1 and an inner tube 2, a substrate holder 4 for holding a silicon single crystal substrate 5, a resistance heating furnace 7. A nozzle tube 8 (for epitaxial growth) for discharging a mixed gas composed of a carrier gas, a silane-based gas and an etching gas, a hydrogen gas, and a single crystal substrate 6 as a doping source on a silicon single crystal substrate 5 in a separate system. It is composed of a nozzle tube 9 (for gas etching) for gas etching only the crystal substrate 6.

The nozzle tube 8 (for epitaxial growth) has a carrier gas such as nitrogen or argon, a silane-based gas such as dichlorosilane, and a hydrogen chloride gas for etching polysilicon deposited simultaneously on the quartz nozzle tube itself during epitaxial growth. A mixed gas consisting only of an etching gas such as the above flows, and the mixed gas is supplied to the plurality of silicon single crystal substrates 5 mounted horizontally at predetermined intervals substantially horizontally through the gas discharge holes 12, Air is exhausted from the exhaust port 11 through the exhaust hole 10. A hydrogen gas is similarly supplied from another nozzle tube 8 (for epitaxial growth), and the two gases are mixed and epitaxially grown on the silicon single crystal substrate 5. A silicon single crystal substrate 6 doped with impurities at a high concentration serving as a doping source is mounted on the upper and lower parts of the group of silicon single crystal substrates 5, and the above mixed gas and hydrogen gas are not supplied on this substrate 6, so that epitaxial growth is performed. do not do. This is realized because the gas discharge holes 12 and the gas discharge holes 10 of the nozzle tube 8 (for epitaxial growth) are not opened at the position of the single crystal substrate 6 of the doping source. Further, an etching gas such as a hydrogen chloride gas and a carrier gas are supplied to the single crystal substrate 6 of the doping source only during the epitaxial growth by the nozzle tube 9 (for gas etching), and the single crystal substrate 6 is etched. The impurities evaporate, and as a result, the impurities are uniformly doped in the epitaxial film grown on the silicon single crystal substrate 5. Since the single crystal substrate 6 as a doping source is mounted on the upper and lower parts of the group of silicon single crystal substrates 5, impurities evaporated by etching during epitaxial growth are almost uniformly deposited on all silicon single crystal substrates 5 by the carrier gas. The uniformity of the supplied epitaxial film resistivity between the surfaces of the silicon single crystal substrate 5 is improved. Further, when a gas flow is formed in the plane of the silicon single crystal substrate 5 so as to optimize the uniformity of the epitaxial film thickness, the flow of impurities in the gas phase is separately controlled, so that the epitaxial film In-plane uniformity of thickness and resistivity can be achieved simultaneously.

An example of growing an epitaxial film using the vapor phase silicon epitaxial growth apparatus according to the present embodiment will be described below. Twelve silicon single crystal substrates 5 each having a diameter of 150 mm are set on the substrate holder 4 at intervals of 8 mm, and a single crystal substrate 6 as a doping source is placed on the upper and lower parts of a group of 12 silicon single crystal substrates 5 by 8 mm each. Set at intervals. The single crystal substrate 6 of the doping source has a diameter of 150 mm.
As a single crystal silicon substrate doped with As and having a resistivity of about 0.003 Ω · cm. 5 rotations per minute (5 rpm
In step m), the substrate holder 4 was rotated, and the temperature inside the reaction tube was set to 1050 ° C. by the resistance heating furnace 7. In the nozzle tube 8 (for epitaxial growth), 200 SCCM of dichlorosilane as a silane-based gas, 150 SCCM of hydrogen chloride gas as an etching gas, and 12 S of nitrogen as a carrier gas.
LM and hydrogen gas 1 from another nozzle tube 8
The flow was at a flow rate of 2 SLM. Further, in order to gas-etch only the single crystal substrate 6 serving as a doping source, 50 SCCM of hydrogen chloride gas and 3 SLM of nitrogen as carrier gas were supplied to the nozzle tube 9 (for gas etching). Growth pressure 10
Under the condition of Torr, an epitaxial film was grown on the silicon single crystal substrate 5 with a thickness of 3 μm and a resistivity of 1 Ω · cm.

The results of the first embodiment will now be described in comparison with the results obtained when an epitaxial film is grown by the conventional apparatus shown in FIG. FIG. 2 shows the dependence of the epitaxial film resistivity at the center of the silicon single crystal substrate 5 on the single crystal substrate mounting position when the conventional growth apparatus and the growth apparatuses of the first embodiment and the second embodiment (described later) are used. FIG. 3 is a view showing the uniformity of the epitaxial film resistivity in the plane of the silicon single crystal substrate 5 in the conventional and the first embodiment.
The single crystal substrate mounting position is a position where the substrate at the lowermost part of the substrate holder is counted toward the uppermost part. However, counting is performed excluding the substrate of the doping source. In FIG. 2, in the conventional growth apparatus, the single crystal substrate mounting position number increases, that is, the epitaxial film resistivity increases toward the downstream side of the nozzle tube 8. Therefore, although the resistivity uniformity is ± 30%, the growth apparatus according to the present embodiment is significantly improved to ± 9%. This is because, in the conventional growth apparatus, the doping gas is mainly released from the upstream side of the nozzle tube 8, so that the pressure loss occurs on the downstream side and the flow rate of the doping gas released from the gas discharge holes 12 decreases. In the growth apparatus of the example, As evaporated by etching from a single crystal substrate of a high-concentration doping source arranged at the upper and lower parts of a group of twelve single crystal substrates stacked horizontally by a carrier gas, 12 As This is because it is supplied almost uniformly to the single crystal substrate. In this embodiment, the single-crystal substrates 5 at the mounting positions 6 and 7 have a higher resistance than the single-crystal substrates 5 at the mounting positions 1 and 12 by about 0.2 Ω · cm. This is because, as the distance increases, the concentration of As vaporized by the etching in the gas phase decreases, and the supply amount of the dopant to the single crystal substrate 5 decreases. However, since the doping source is mounted one below the single crystal substrate 5 at the mounting position 1 and one above the single crystal substrate 5 at the mounting position 12, the same nozzle tube is used for all twelve single crystal substrates 5. Compared with the conventional technique of supplying the dopant at 8, the inter-substrate resistivity uniformity of all 12 single-crystal substrates 5 is improved.

In FIG. 3, the uniformity of the epitaxial film resistivity in the plane of the single crystal substrate is ± 16% in the conventional growth apparatus, while it is remarkably improved to ± 2% in the growth apparatus of the present embodiment. At this time, the uniformity of the epitaxial film thickness in the plane of the single crystal substrate is optimized at ± 2%. When the flow of dichlorosilane and carrier gas is optimized to improve the uniformity of the epitaxial film thickness in the plane of the single crystal substrate, the phosphine gas is mixed with the same carrier gas at the same time in the conventional growth equipment. Since the diffusion coefficient in the carrier gas differs from that of the phosphine gas, the flow of the phosphine gas is not always optimal. On the other hand, in the growth apparatus of this embodiment, since the flow of dichlorosilane and As evaporated from the doping source are independently controlled, the flow of gas is controlled so that the uniformity of the film thickness and the uniformity of the resistivity are optimized simultaneously. In this embodiment, the etching gas and the carrier gas flow rate are selected so as to optimize the resistivity uniformity in the substrate surface, and the in-plane uniformity of ± 2% is obtained. I have.

Since the doping source itself is not epitaxially grown, the above effect can be obtained even if the same doping source is used many times.

Next, a second embodiment of the present invention will be described. FIG. 4 is a longitudinal sectional view of a second embodiment of the present invention. The single crystal substrate 6 as a doping source is arranged at the upper, middle and lower parts of the single crystal substrate 5 divided into upper and lower groups, and gas discharge holes of the nozzle tube 9 (for gas etching) are opened only at the corresponding positions. The gas discharge holes 12 and the gas discharge holes 10 of the nozzle tube 8 (for epitaxial growth) were not opened at those positions. Except for this, all the operations were the same as in the first embodiment.

FIG. 2 shows the dependency of the epitaxial film resistivity on the single crystal substrate mounting position when grown using the conventional apparatus, the first embodiment, and this embodiment. The characteristics are ± 4%, which is improved compared to ± 9% of the first embodiment. This is because the supply of As to the 12 single-crystal substrates 5 everywhere is further promoted by disposing the doping source between the upper half and the lower half of the group of single-crystal substrates 5. That is, in the first embodiment, the concentration of evaporated As in the vapor phase decreased due to etching as the distance from the doping source increased. However, such a phenomenon was suppressed by disposing the doping source as described above. In the embodiment, the uniformity of the resistivity between the substrates is improved as compared with the first embodiment. Further, by further increasing the number of doping sources disposed between the groups of the single crystal substrates 5 or above and below, the uniformity of the resistivity between the substrates is further improved.

[0017]

As described above, in the vapor phase silicon epitaxial growth apparatus according to the present invention, the upper and lower portions of a group of a plurality of silicon single crystal substrates horizontally mounted at predetermined intervals are doped with a high concentration of impurities. By arranging a single crystal substrate of the source and preventing an epitaxial film from growing thereon, and by arranging a nozzle tube dedicated to gas etching such that only the single crystal substrate of the doping source is gas-etched during the epitaxial growth, This has the effect of simultaneously improving the inter-plane uniformity and the in-plane uniformity of the epitaxial film resistivity between the single crystal substrates. This is because the As which has been etched and evaporated from the upper and lower doping sources of a plurality of single crystal substrates is almost uniformly supplied to all the single crystal substrates during the epitaxial growth. This is because the in-plane uniformity of the film resistivity of the single crystal substrate can be optimized independently. Further, by arranging the doping source also in the upper part, the middle part, and the lower part of the single crystal substrate group vertically divided, the uniformity of the epitaxial film resistivity between the single crystal substrates is improved. This is because the variation in the concentration of evaporated As due to the etching of the doping source was improved between the substrates, and the supply of the dopant to the plurality of single crystal substrates became more uniform.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of the present invention.

FIG. 2 is a diagram showing the dependence of the epitaxial film resistivity on the silicon single crystal substrate mounting position when the first and second embodiments of the present invention and a conventional vapor phase silicon epitaxial growth apparatus are used.

FIG. 3 is a diagram showing the uniformity of the epitaxial film resistivity when the first embodiment of the present invention and a conventional vapor phase silicon epitaxial growth apparatus are used.

FIG. 4 is a longitudinal sectional view of a second embodiment of the present invention.

FIG. 5 is a longitudinal sectional view of a conventional vapor phase silicon epitaxial growth apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 3 Stand 4 Substrate holder 5 Single crystal substrate 6 Single crystal substrate of doping source 7 Resistance heating furnace 8 Nozzle tube (for epitaxial growth) 9 Nozzle tube (for gas etching) 10 Gas exhaust hole 11 Exhaust port 12 Gas Release hole

Claims (3)

(57) [Claims] A plurality of vapor-grown silicon substrates are held horizontally at predetermined intervals so as to be horizontally stacked, and a plurality of epitaxial growth nozzle tubes having a plurality of gas emission holes are provided. A gas mixture comprising a silane-based gas, an etching gas, and a carrier gas and a hydrogen gas are flowed from different nozzle tubes substantially in parallel to the respective vapor-deposited growth surfaces of the phase-grown silicon substrate, and In a vapor phase silicon epitaxial growth apparatus for vapor-phase growing an epitaxial film, there is provided a single crystal substrate doped with impurities at a high concentration as a doping source for the epitaxial film, and this is mounted simultaneously with the silicon substrate to be vapor-deposited. Providing a gas etching nozzle tube for gas etching only the doping source during the epitaxial growth. A vapor-phase silicon epitaxial growth apparatus characterized in that the epitaxial growth nozzle tube is not provided with a gas discharge hole for epitaxial growth to the doping source. 2. The vapor-phase silicon epitaxial growth apparatus according to claim 1, wherein a single-crystal substrate doped with a high concentration of impurities as a doping source for the epitaxial film is arranged above and below the vapor-deposited silicon substrate group. 3. A single crystal substrate doped with a high concentration of impurity as a doping source for the epitaxial film is disposed at an upper part, an intermediate part, and a lower part obtained by vertically dividing the vapor-deposited silicon substrate group into two parts. 2. The apparatus for vapor-phase silicon epitaxial growth according to claim 1.