JPH0718441U - Thin film vapor deposition equipment - Google Patents

Abstract

(57) [Summary] [Purpose] In a vertical thin-film vapor deposition apparatus, a raw material gas is blown from the narrow top entrance. The cross-sectional area of the gas flow channel widens downward. In the vicinity of the substrate, the flow is large in the center and small in the peripheral portion. As a result, the thickness of the vapor-deposited thin film is thick in the center and thin in the peripheral portion, resulting in nonuniformity. Solve this. [Configuration] Reactor - gas inlet tube T ₁ independent to the inlet of the raw material _{gas, T 2, T 3, ...} , provided the concentric multiple tube is a collection of T _N. Mass flow controllers M ₁ , M ₂ , M ₃ , ..., _MN are provided in the respective gas introduction pipes so that the flow rate can be adjusted independently. By independently changing the flow rates W ₁ , W ₂ , W ₃ , ..., W _N , it is possible to realize an arbitrary gas supply amount distribution in the radial direction. The uniformity of the film thickness and composition of the thin film can be improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thin film vapor deposition apparatus that optimizes the flow of raw material gas. The thin film vapor deposition apparatus is an apparatus for forming a thin film on a substrate by causing a source gas to flow on a heated substrate and causing a vapor phase reaction on the substrate. There are a reactor which is a reaction vessel, a susceptor provided inside the reactor, a heater for heating the susceptor, a source gas introduction pipe for supplying a source gas to the reactor, and a gas discharge device. As the gas, hydrogen gas is used as a carrier gas in addition to the raw material gas.

[0002]

[Prior art]

 The thin film vapor deposition apparatus is classified into a vertical type and a horizontal type depending on the shape of the reactor and the flow of gas. Here, a vertical thin film vapor phase growth apparatus is targeted. FIG. 4 is a schematic cross-sectional view of a vertical thin film vapor phase growth apparatus according to a conventional example.

There is a vertical reactor-1 having a cylindrical shape in the lower part and a reduced diameter in the upper part. The raw material gas enters from the narrow upper top portion 2 of the reactor and flows downward. In the reactor-1, a susceptor 3 having a horizontal plane is provided supported by a rotating shaft 4. A substrate 5 is horizontally placed on the susceptor 3. The rotating shaft 4 rotates slowly so that the film thickness and film quality of the thin film are constant in the circumferential direction. Due to the rotation of the susceptor, there is almost no problem in the uniformity in the circumferential direction.

A high-frequency heating coil 6 is provided at the same height as the susceptor on the outer peripheral portion of the reactor-1 to induction-heat the susceptor. The heating mechanism is not limited to the high frequency coil, but may be resistance heating or lamp heating. In the case of high frequency heating or lamp heating, make a reactor with quartz. In the case of resistance heating, the reactor can be made of stainless steel or Al. Waste gas and unreacted gas are discharged by a vacuum pump (not shown) through a gas discharge pipe.

The source gas flows from top to bottom and hits the substrate 5 on the way. Since the temperature of the substrate is high, a gas phase reaction occurs here, and the product is formed as a thin film on the substrate. The gas flow path is narrow at the top, gradually widens at the shoulder, and has the same cross-sectional area below the middle. However, since the gas is the gas that flows on the inner surface of the cylinder, the velocity near the wall is slow and the velocity is fast in the center due to viscous drag on the wall. The speed at which the source gas hits the substrate is different.

More gas is supplied in the central part, and less gas is supplied in the peripheral part. The formation of the thin film is almost proportional to the gas supply amount. Therefore, the film thickness of the thin film differs between the central part and the peripheral part. Thin at the periphery and thick at the center. The difference in thickness is several% to several tens%. Sometimes it reaches 50%. If the thickness of the thin film is not uniform, the characteristics of the device manufactured using it will also vary. This has to be improved.

As described above, the vertical device has good rotational symmetry, but has a drawback that the uniformity of film thickness and film quality in the radial direction is poor. However, it seems that such non-uniformity in the radial direction has not been a problem so far, and there is almost no invention devised for this. Japanese Utility Model Publication No. 3-29333 has a problem of the difference between the velocity near the wall surface and the velocity at the central portion. In order to reduce the gas flow velocity at the central portion, as shown by the broken line in FIG. A spindle-shaped commutator is suspended directly above. For this purpose, an operating rod is provided through the wall surface of the reactor. The source gas flowing in the central part hits the commutator, so the speed is slightly reduced. Therefore, the distribution of gas supply becomes uniform in the horizontal cross section.

[0008]

[Problems to be solved by the device]

 The problem of non-uniformity of the gas supply distribution in the radial direction does not become a problem when the gas flow velocity is slow. However, as the gas flow rate increases, the non-uniform gas supply becomes severe, causing fluctuations in the film thickness and composition of the thin film, which has an effect. This is a problem that needs to be resolved.

The above-mentioned Japanese Utility Model Publication No. 3-29333 said that the spindle-shaped commutator was suspended in the upper center of the reactor to make the flow velocity distribution uniform. However, it is unlikely that the flow velocity distribution will improve at that level. As a first approximation, the fluid flowing in a cylindrical tube can be considered to have a Poiseuille flow. This assumes that the flow velocity is expressed as a quadratic function in which the maximum value at the center is 0 on the wall surface. Actually, higher order 4th and 6th order terms may be included. Even if it is as simple as a quadratic function, it is not possible to make the radial velocity distribution uniform by just hanging the commutator in the center. On the contrary, it may disturb the gas flow in the central part and disturb the gas phase reaction.

Further, it is necessary to pass the operating rod from the outside through a reactor which is a vacuum container. This would be a difficult mechanism if the reactor were quartz. In addition, the operating rod may disturb the gas flow. Japanese Utility Model Publication No. 3-29333 is incomplete as a device for making the gas flow uniform.

It is an object of the present invention to provide a thin film vapor deposition apparatus capable of making the gas flow velocity uniform in the radial direction without disturbing the gas flow.

[0012]

[Means for Solving the Problems]

 In the thin film vapor phase growth apparatus of the present invention, the source gas is supplied by a concentric multiple tube which is a collection of gas introduction tubes, and a mass flow controller is provided in each of the multiple tubes to multiplex the flow rate of the source gas. The tubes are independently controlled so that the gas supply amount distribution inside the reactor is made uniform in the radial direction. A perforated plate is provided at the opening of the reactor of the concentric multi-tube, and a plurality of holes are equidistantly formed in the perforated plate so that the gas is uniformly blown out in the circumferential direction. It is desirable to make the top of the reactor with the concentric multiple tubes wider than the conventional one, but even with the same level as the conventional one, by controlling the gas supply amount, the gas supply amount distribution when blown into the reactor can be controlled. You can do the same.

[0013]

[Action]

At the top opening of the reactor, a concentric multiple tube, which is a collection of N independent gas introduction tubes, is provided. The gas introduction pipes are T ₁ , T ₂ , T ₃ , ..., T _N. A pipe is connected to each concentric multiple pipe, and the same raw material gas and carrier gas are made to flow independently through this pipe. Path X _1, X _2, X ₃ leading to the concentric multiple tube, ..., mass flow to the X _N - controller - La _{M 1, M 2, M 3} , ..., provided M _N. The flow rate can be controlled independently by the mass flow controller and becomes W ₁ , W ₂ , W ₃ , ..., W _N , respectively. The flow of the raw material gas controlled independently from the N concentric channels is supplied to the reactor. The central flow rate W ₁ is made relatively small, and the flow rates are increased in the order of W ₁ , W ₂ , W ₃ , ..., W _N. Then, even if there is resistance on the wall surface after entering the reactor, when it reaches the substrate, a uniform flow occurs in the radial direction.

The advantage of the present invention is high controllability. Since the flow rates of the N concentric multiple tubes can be independently controlled, the gas supply amount distribution near the substrate can be set arbitrarily. The optimum flow rate combination can be obtained by measuring the gas supply amount distribution in the vicinity of the substrate while changing W ₁ , W ₂ , W ₃ , ..., W _N.

[0015]

【Example】

 FIG. 1 is a vertical sectional view of a thin film vapor deposition apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged transverse sectional view of a portion of the concentric multi-tube. There is a susceptor 3 inside the vertically long reactor-1. The susceptor 3 can be rotated by a rotating shaft 4. The substrate 5 is placed on the susceptor 3 and heated by the high frequency heating heater 6. Waste gas and unreacted gas are discharged from the lower gas discharge port 7. Such a structure is the same as the conventional vertical type device. However, the part where the source gas is introduced is different.

The upper top portion 2 of the reactor-1 is wide, and a concentric multiple pipe 8 is attached to it. This is a group of independent gas introduction pipes T ₁ , T ₂ , T ₃ , ..., T _N. An inlet plate 9 is fixed to the lower end of the concentric multiple pipe 8. The inlet plate 9 is perforated with a large number of pores 10. The raw material gas enters the inside of the reactor-1 from the independent gas introduction pipes T ₁ , T ₂ , T ₃ , ..., T _N through the pores 10. Although the case where N = 3 is shown here, N may be any of 4, 5, 6, 7 ...

Gas introduction pipe T of concentric multiple pipe 8₁ , T₂ , T₃ , ..., T_N Is an independent path X₁ , X₂ , X₃ , ..., X_N Is connected to the manifold 11 via. Raw material gas flows in here, and N routes X₁ , X₂ , X₃ , ..., X_N Is separated into Mass flow controller M for flow rate control for each route₁ , M₂ , M₃ , ..., M _N Is provided. This is the flow rate W₁ , W₂ , W₃ , ..., W_N Control the gas introduction pipe T₁ , T₂ , T₃ , ..., T_N Adjust the flow rate at. The reason for forming the pores 10 in the inlet plate 9 at equal intervals is to blow out the gas uniformly in the circumferential direction.

As shown in FIG. 2, it is assumed that the pores are distributed with an appropriate density corresponding to the T ₁ , T ₂ , T ₃ , ..., T _N gas introduction pipes. The flow rates W ₁ , W ₂ , W ₃ , ..., W _N can be strictly controlled by a mass flow controller. By controlling the flow rate with a mass flow controller, a uniform gas supply amount distribution can be realized in any radial direction.

FIG. 3 shows an example of the gas supply amount distribution in the radial direction. The vertical axis is the gas supply amount and the horizontal axis is the radial position. This is the gas supply amount distribution of the gas directly above the substrate. (A) is large in the central portion O and small in the peripheral portion. This is the conventional gas flow. (B) is the same in the central portion O and the peripheral branches P and Q, and the gas supply amount is completely uniform. The present invention can realize this. On the other hand, (c) is faster in the peripheral area. According to the present invention, such an inversion distribution can be realized. (D) is large in the peripheral part of the substrate and small in the wall and the center. In this way, the present invention can positively create an arbitrary gas supply amount distribution.

[0020]

[Effect of device]

This invention is, in the vertical thin-film vapor deposition apparatus, a raw material gas is performed through a concentric multi-tube, a gas flow rate of the concentric multiple tube _{W 1, W 2, W 3} , ..., a W _N, mass flow - Since it is set appropriately by controlling the controller, it is possible to realize an arbitrary gas supply amount distribution. Instead of suspending an obstructive object in the gas flow, it does not disturb the flow.

Since the vertical thin-film vapor deposition apparatus rotates the susceptor around the rotation axis, there is no problem with the uniformity of the film thickness in the circumferential direction. The present invention utilizes such a property, and by introducing a controlled flow rate of the raw material gas from the concentric multi-tube, an optimum flow rate distribution can be realized in the vicinity of the substrate. When a thin film is formed by such an apparatus, the film thickness and the uniformity of film composition are greatly improved. Since uniform film formation is possible, when making an electronic device using this thin film, a device with uniform characteristics can be produced, and the device manufacturing yield is also increased. It is an excellent idea.

According to the present invention, not only can the gas supply amount near the substrate be made constant, but the flow velocity at the center can be reduced and the flow velocity at the periphery can be increased. Another advantage is that it is easy to select the optimum conditions for thin film formation.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a thin film vapor deposition apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of a portion of the concentric multi-tube shown in FIG.

FIG. 3 is a graph showing that an arbitrary gas supply amount distribution can be realized by the raw material gas introduction mechanism of the present invention. (A) is large in the central portion O and is small in the peripheral portion, (b) is the same in the central portion O and the peripheral branches P, Q, and the gas supply amount is completely uniform, (c) is A large amount in the peripheral portion, (d) shows a large amount in the peripheral portion of the substrate and a small amount in the wall and the center.

FIG. 4 is a schematic cross-sectional view of a thin film vapor deposition apparatus according to a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Reactor 2 Top part 3 Susceptor 4 Rotating shaft 5 Substrate 6 High frequency heating coil 7 Gas discharge pipe 8 Concentric multiple pipe 9 Inlet plate 10 Pore 11 Manifold M ₁ , M ₂ , M ₃ , ..., _MN mass flow - controller - La _{X 1, X 2, X 3} , ..., leading to X _N concentric multi-tube pathway

Claims (2)

[Scope of utility model registration request] 1. A vertically long cylindrical reactor-1, a susceptor 3 provided inside the reactor-1 for mounting a substrate, a heater for heating the susceptor-3, and a vacuum inside the reactor. Device for pulling to the reactor and reactor-1
Concentric gas introduction tube T attached to the opening at the top of the
Concentric multi-tube 8 which is a collection of ₁ , T ₂ , T ₃ , ..., T _N
And independent introduction pipes T ₁ , T ₂ , T _{3 of} the concentric multi-pipe 8,
..., paths X ₁ and X ₂ for introducing the same source gas to T _N
, X ₃ , ..., X _N and each path X ₁ , X ₂ , X ₃ ,.
Mass flow for controlling the flow rate of the gas provided in the middle of the X _N - controller - La _{M 1, M 2, M 3} , ..., and a M _N, the raw material gas path _{X 1, X 2, X 3} , ..., X _N, and is divided into mass flow controllers M ₁ , M ₂ , M ₃ , ..., M
_{, N} through the independent introduction pipes T ₁ , T ₂ , T ₃ , ..., _TN to enter the inside of the reactor-1 and reach the substrate for gas phase reaction. M ₁ ,
A thin film vapor phase growth apparatus characterized in that the gas supply amount distribution of the source gas near the substrate 5 is controlled by M ₂ , M ₃ , ..., _MN . 2. A vertically long cylindrical reactor-1, a susceptor 3 provided inside the reactor-1 for placing a substrate, a heater for heating the susceptor-3, and a vacuum inside the reactor. Device for pulling to the reactor and reactor-1
Concentric gas introduction tube T attached to the opening at the top of the
Concentric multi-tube 8 which is a collection of ₁ , T ₂ , T ₃ , ..., T _N
An inlet plate 9 having a large number of pores 10 provided in the lower part of the concentric multi-tube 8, and independent introduction tubes T ₁ , T
_2, T _3, ..., the path X ₁ for introducing the same raw material gas to _{T N, X 2, X 3} , ..., and X _N, each path X _1, X _2,
X _3, ..., the mass flow for controlling the flow rate of the gas provided in the middle of the X _N - controller - La _{M 1, M 2, M 3} , ...,
, M _N , and the source gas is route X ₁ , X ₂ , X ₃ , ...,
Divided into X _N , mass flow controller M ₁ , M ₂ , M
₃ , ..., M _N , independent inlet pipes T ₁ , T ₂ , T ₃ ,
, _TN to enter the inside of the reactor-1 and reach the substrate to cause a gas phase reaction, and the substrate 5 is moved by the mass flow controllers M ₁ , M ₂ , M ₃ , ..., _MN. A thin film vapor phase growth apparatus characterized in that a gas supply amount distribution of a raw material gas is controlled in the vicinity of.