JPH02275797A - Gas phase growth device - Google Patents

Abstract

PURPOSE:To uniform the pressure distribution of a gas in a gas phase growth device to uniform the thickness of a formed epitaxial film by disposing a plurality of gas inlets in the wall of the main body of a horizontal style-gas phase growth device and controlling the flow rate of each gas inlet on the basis of the measurement result of a gas pressure near the each gas inlet. CONSTITUTION:A plurality of gas inlets 12a, 12b, 12c, etc., are disposed in a wall between a sucepta 4 loading wafers 3 thereon in a horizontal style gaseous growth device 2 and a raw material gas-feeding opening 6. A plurality of pressure gauges 13a, 13b, 13c, etc., are further disposed in a wall facing the first wall. The wafers 3 and the sucepta 4 are heated with a heater 5 and the raw material gas is fed horizontally in the direction of the arrow D to form epitaxial films on the surfaces of the wafers 3. In the process, gas pressures are measured with a plurality of pressure gauges 13a, etc., and a control mechanism 8 is operated based on prescribed pressure values to control flow rate regulators 17a, etc., disposed in the gas inlets 12a, etc., for the regulation of the flow rate, thereby uniforming the pressure distribution in the device 2 to uniform the flow rate distribution of the raw material gas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vapor phase growth apparatus for forming an epitaxial film on a wafer surface, and particularly to a so-called horizontal vapor phase growth apparatus.

Conventional wave 't- and its challenges Epitaxial film refers to a thin film formed by using a single crystal such as silicon as a substrate (wafer) and growing a single crystal on top of it in a vapor phase.The formation of this epitaxial film is・It is one of the important steps in the manufacturing process of IC devices such as CCD, Bi-CJ40S, etc.

Conventionally, a type of vapor phase growth apparatus called a horizontal vapor phase growth apparatus has been widely used for forming this type of epitaxial film.

The horizontal vapor phase growth apparatus forms an epitaxial film on the wafer surface by flowing source gas from a substantially horizontal direction onto the surface of the wafer disposed within the apparatus main body.

This epitaxial film is required to have a uniform film thickness distribution so that there is no variation in performance between products.

By the way, in the vapor phase growth apparatus, it is known that the growth rate of the film increases as the flow rate of the source gas flowing through the apparatus main body increases (J, Electroche
m, Soc, :5OLID 5TATE S to IEN
CE Vo1.117. No. 7.1970. p.925
- p, 930 F, C, Eversteynet a
l, see).

This is thought to be related to the thickness of the stagnant layer, and when a source gas is flowed horizontally to the wafer surface, the thickness of the stagnant layer in the laminar flow that determines the growth rate of the thin film increases. The raw material gas is consumed as it progresses from the supply side to the outlet side. For this reason, the raw material gas concentration gradually becomes thinner, leading to non-uniformity in film thickness distribution in the flow direction of the raw material gas.

However, by rotating the susceptor on which the wafer is placed, the film thickness distribution in the circumferential direction can be made uniform, and it is possible to make the film thickness distribution uniform to some extent in the flow direction of the raw material gas. be. Therefore, if the growth rate of the film in the direction perpendicular to the flow direction of the source gas in the apparatus main body (hereinafter referred to as the lateral direction) is made uniform, an epitaxial film with a uniform thickness distribution can be formed on the wafer surface. It becomes possible to do so. In other words, if the growth rate of the film in the lateral direction within the device body is made uniform, the film thickness distribution in the radial direction of the susceptor will also be made uniform, and the film thickness distribution will be uniform in both the circumferential direction and the radial direction. This is because the results are made uniform.

Therefore, if the velocity of the source gas in the lateral direction within the apparatus main body is made uniform, it becomes possible to make the growth rate of the film uniform.

On the other hand, when the raw material gas is flowed horizontally from the supply side, as shown in FIG. There is.

Because the velocity distribution draws a substantially parabolic curve P in this way, the film thickness distribution in the radial direction (direction indicated by arrow y) on the surface of the converter 60 on which the wafer 52 is placed is uneven, especially in large-sized vapor phase growth apparatuses. becomes.

A known method for making the film thickness distribution uniform is to provide a plurality of nozzles on the side wall of the device body and appropriately adjust the flow rate discharged from these nozzles to make the velocity distribution uniform ( (not shown).

However, it is technically difficult to adjust the flow rate of the nozzle with high precision, and even when the flow rate is adjusted fairly well, there may be uneven flow (one-sided flow).

When such a biased flow occurs, various problems occur in film formation, such as generation of eddies, and there is a problem that an epitaxial film having a uniform film thickness distribution cannot be obtained.

The present invention has been made in view of these problems, and it is a gas that can uniformize the velocity distribution of the source gas within the IR body and form an epitaxial film with a uniform thickness distribution on the wafer surface. The purpose of the present invention is to provide a phase growth device.

In order to achieve the above-mentioned object, a vapor phase growth apparatus according to the present invention has a vapor phase growth apparatus according to the present invention, in which a source gas is flowed from a substantially horizontal direction to a wafer surface disposed in an apparatus main body, and a source gas is flowed onto the wafer surface. In a vapor phase growth apparatus in which an epitaxial film is formed, a plurality of intake ports are provided in a wall of the apparatus main body between a susceptor on which the wafer is placed and an introduction hole for the source gas. In addition, a plurality of pressure gauges for measuring pressure are provided on a wall portion opposite to the wall portion, and a control mechanism controls the pressure within the device main body based on the measured values of the plurality of pressure gauges, It is characterized in that it is connected to the intake port, and that the control mechanism includes a flow meter for measuring the amount of intake air.

5■ It is generally known that the following Bernoulli equation holds true for inviscid fluids.

P+ (pv2/2)+pgZ=constant...■Here, P: pressure, ρ: fluid density, ■=flow velocity, Z: height, g
:Z=0 because there is no deviation in the height direction in the gravitational acceleration horizontal vapor growth apparatus. Therefore, by measuring the pressure P, the flow rate that controls the growth rate of the epitaxial film can be determined. That is, by appropriately controlling the pressure, the flow rate can be controlled in accordance with the pressure.

Therefore, according to the above configuration, the pressure of the plurality of intake ports arranged on the wall of the main body of the device is measured by the pressure gauge provided on the wall opposite to the wall, and furthermore, these pressure measurement values are Since a control mechanism that controls the pressure within the apparatus main body based on the above is connected to the intake port, it is possible to equalize the pressure distribution within the apparatus main body.

By equalizing the pressure distribution within the apparatus main body, the flow velocity distribution of the raw material gas is equalized, and an epitaxial film having a uniform thickness distribution is formed on the surface of the sea urchin.

Furthermore, since the control mechanism includes a flow meter for measuring the amount of intake air, it is possible to appropriately feed back the measured value of the amount of intake air to the source gas supply side. Therefore, it is possible to always keep the flow rate of the source gas introduced into the apparatus main body at a constant flow rate, and it is possible to prevent fluctuations in the flow rate of the source gas introduced into the apparatus main body.

Hereinafter, embodiments of the vapor phase growth apparatus according to the present invention will be described in detail with reference to the drawings.

1 and 2, reference numeral 1 denotes a horizontal vapor phase growth apparatus as an example of a vapor phase growth apparatus according to the present invention, which comprises an apparatus main body 2 made of quartz and a plurality of wafers 3... A susceptor 4 is placed on the surface, a heater section 5 is disposed above and below the device main body 2 to heat the inside of the device main body 2, and a gas nozzle section 6 is provided at the tip of the susceptor 4, which contains raw material gas (including carrier gas). ) into the apparatus main body 2, and a control mechanism 8 that appropriately controls the pressure of the raw material gas in the apparatus main body 2.

The apparatus main body 2 includes a reaction tube 9 having a rectangular cross section and an injection pipe 7.
and an exhaust section 11 that exhausts unreacted raw material gas in the six directions of arrows.

The bottom plate 25 of the reaction tube 9 has first to fifth intake ports 12a to 1.
2e is arranged. Specifically, these intake ports 12
a to 12e are arranged at intermediate positions between the raw material gas introduction hole connected to the injection pipe 7 and the susceptor 4, near the susceptor 4, and at regular intervals in the width direction of the device main body 2 (indicated by arrow Y). has been done. Further, first to fifth pressure gauges 13a to 13e for measuring the pressure inside the main body of the apparatus are provided at positions facing the intake ports 12a to 12e. The reason why the suction port and the pressure gauge are provided near the susceptor 4 is to measure the pressure as close as possible to the pressure on the susceptor 4 and control the pressure in order to control the flow rate of the raw material gas in the device main body 2. This is because it is advantageous for controlling the distribution.

In this embodiment, as shown in FIG.
-12e are arranged linearly in plan view, but in another embodiment, they may be arranged semicircularly along the outer periphery of the susceptor 4.

Further, the positional relationship between the intake port and the pressure gauge does not necessarily have to be such that they are substantially vertically opposed to each other. Even if the positions of the two are shifted, it is possible to make the flow velocity distribution of the source gas uniform by making corrections.

The susceptor 4 is made of carbon coated with silicon carbide, has a circular shape in plan view, and is rotatable in the direction of arrow C. 14 is a bearing seal portion of the susceptor 4.

The heater section 5 includes a plurality of infrared lamps 15...
It is constructed mainly of a reflecting plate 16 that reflects the heat of these infrared lamps 15 and contributes to heating the inside of the device main body 2.

Thus, the control mechanism 8 controls the first to fifth flow rate regulating valves 17a to 1 which control the exhaust flow rate from the intake ports 12a to 12e.
7e, a flow rate measuring device 18 that measures the flow rate from the intake ports 12a to 12e, and a flow rate control section 19 that controls the flow rate of the raw material gas supplied to the apparatus main body 2. Further, first to fifth intake pipes 20a to 20e are provided with the flow rate regulating valves 17a to 17e at intermediate positions.
are joined to the - intake pipes 21 and connected to the flow rate measuring device 18.

Further, the flow rate control section 19 is provided in the injection pipe 7 and controls the supply flow ff1V to the apparatus main body 2. A first flow rate controller 23a that controls the exhaust flow rate VE for exhausting part of the source gas in the direction of the arrow E, and a second flow rate controller 23 that controls the exhaust flow rate VE for exhausting part of the source gas in the direction of the arrow E.
b.

In the vapor phase growth apparatus configured in this manner, an epitaxial film is formed on the surface of the sea urchin in the following manner.

First, after placing a plurality of wafers 3 on the susceptor 4, the susceptor 4 is rotated in the direction of arrow C, and
Heat the wafer 3... and susceptor 4 to about 1000°C by turning the power supply of the heater section 5 on.
A raw material gas consisting of a carrier gas such as He is conveyed from the direction of the arrow. Then, this raw material gas is used for wafer 3...
When reaching the upper surface of the wafer 3, the silicon-based gas undergoes a decomposition reaction due to the heat from the heater section 5, and silicon is deposited on the surface of the wafer 3, forming an eclipse.

Therefore, in the present invention, in order to obtain a uniform film thickness distribution, the pressure at each point within the apparatus main body 2 is made uniform via the control mechanism 8, and the velocity distribution of the raw material gas within the apparatus main body 2 is made uniform. It is structured so that the

The control mechanism 8 will be explained below.

When raw material gas is supplied into the apparatus main body 2 from the gas nozzle section 6 provided at the tip of the injection pipe 7, the velocity distribution generally follows a parabola P, as described in the section of "Prior art and its problems".
(See Figure 3).

In other words, the flow velocity is maximum at the central position corresponding to the third intake port L2c, and according to the Bernoulli equation (equation 0) described in the "effect" section, the flow velocity is maximum at the position corresponding to the third intake port 12c. pressure is at its lowest.

Therefore, when the third flow rate regulating valve 17c is set to the "open" state and a part of the raw material gas is exhausted from the third intake port 17c,
In the central region, the flow rate decreases while the pressure increases. In the present invention, the first to fifth flow rate regulating valves 17a to 17e are arranged such that the pressure values measured by the first to fifth pressure gauges 13a to 13e are all the same pressure.
The opening degree is adjusted, and the pressure distribution within the device main body 2 is made uniform. For example, when the pressures at the first intake port 12a and the fifth intake port 12e are at desired set pressures, the pressure value at the third intake port 12c is determined by the third pressure gauge 13.
When measured by c, the pressure value is converted into an electrical signal and input to the third flow rate regulating valve 17C. Then, the opening degree of the third flow rate regulating valve 17c varies according to the electric signal, and the opening degree is adjusted so that the pressure value is the same as that of the first pressure gauge 13a and the fifth pressure gauge 13e. , the pressure distribution within the device main body 2 is made uniform.

In addition, the supply flow MV of the raw material gas supplied into the apparatus main body 2
o is controlled via the flow rate control unit 19 so that the flow rate is constant.
ll f can be sold. That is, for example, when the third flow rate regulating valve 17c is set to the "open" state, the third
Since the flow rate VX is exhausted from the intake port L2c, the supply flow rate v of the raw material gas.

Although there is a possibility that the supply flow By may vary, in this embodiment, the supply flow By is controlled via the flow rate control section 19. is discharged so that the flow rate is always constant.

That is, the desired supply flow rate is V. In this case, the flow rate of the raw material gas conveyed from the direction of the arrow is set to (V>Vo), and the flow rate ZVA (=V-V,) is set to VA>
Under the condition of Vx, the second flow rate controller 23b is evacuated. When the flow rate Vx exhausted from the third intake port 12c is detected by the flow rate measuring device 8, the flow rate VX is converted into an electric signal and sent to the second 7M amount controller 23b.
sent to. Then, the flow rate exhausted from the second flow rate controller 23b is set to V, =VA-V, and the supply flow iV. is always maintained at the desired constant flow rate. In other words, the flow rate exhausted from the second flow rate controller 23b is increased by the flow rate VX exhausted from the third intake port 17c, which is the initial exhaust flow rate v.
By not decreasing from A, the supply flow rate V. can always be maintained at the desired flow rate.

In this way, in the above embodiment, the supply flow rate vo is always maintained at a constant flow rate, and the plurality of pressure gauges 13a to
Since the control mechanism 8 is provided to control the measurement values measured by the device 13e to be all the same value, the pressure distribution inside the device body 2 is equalized, and therefore the pressure distribution inside the device body 2 is equalized.
The velocity distribution of the raw material gas within the chamber is also made uniform, and the supply flow rate does not change. That is, the growth rate of the film is made uniform, and an epitaxial film having a uniform film thickness distribution is formed on the surface of the wafer 3 placed on the susceptor 4, thereby obtaining a highly reliable and high quality IC device such as a CCD. be able to.

It goes without saying that the present invention is not limited to the above-mentioned embodiments, and may be modified without departing from the scope of the invention. In the above embodiment, the first and fifth intake ports 20a, 2
Although the pressure at 0e is set as the desired pressure, the pressure inside the main body 2 of the device can be easily equalized in the same way even if other intake ports, such as the second intake port 20b and the fourth intake port 20d, are set to the desired pressure. I can do it. Furthermore, instead of forming the intake port on the bottom plate 25 of the reaction tube 9, it may be formed on the top plate 26 of the reaction tube 9 and a pressure gauge may be attached to the bottom plate 25 of the reaction tube 9. It is possible to achieve the following effects.

Furthermore, it goes without saying that the present invention can similarly perform highly accurate pressure control even when five or more intake ports are provided, and is advantageous for large-sized devices that tend to cause non-uniform velocity distribution. It is something.

Furthermore, in the above embodiment, the suction ports and the pressure gauges are provided at vertically opposing positions, and the pressure at the position corresponding to each suction port is controlled to be the same, thereby making the flow velocity distribution of the raw material gas uniform. Ta. However, the positions of the intake port and the pressure gauge do not necessarily have to be vertically opposed, and the intake port may be provided along the outer periphery of the susceptor, as described above. in this case,
If the measured values of each pressure gauge are controlled to be the same value, the flow velocity distribution of the raw material gas on the surface of the sea urchin will become even more uniform, and the surface of the sea urchin will have a more even layer of epitaxial film. can be formed.

Further, in the present invention, the gas in the high pressure region is sucked to make the flow velocity distribution uniform. However, it is also possible to make the flow velocity distribution uniform by supplying the raw material gas to a region where the pressure is low. In this case, care must be taken to prevent the particles deposited in the apparatus main body 2 from being rolled up by the introduced gas and contaminating the epitaxial film.

As described in detail above, the vapor phase growth apparatus according to the present invention includes a plurality of air inlets arranged on the wall of the main body of the apparatus, and
A plurality of pressure gauges for measuring pressure are provided on a wall opposite to the wall. Furthermore, since a control mechanism that controls the pressure inside the device main body based on the measured values of the plurality of pressure gauges is connected to the intake port, the pressure distribution inside the device main body can be made uniform, and the device The velocity distribution of the raw material gas within the main body can be easily made uniform.

Therefore, the growth rate of the film is also made uniform, and an epitaxial film having a uniform thickness can be formed on the surface of the sea urchin placed on the susceptor.

As described above, according to the vapor phase growth apparatus according to the present invention, by equalizing the pressure distribution within the apparatus main body, the flow velocity of the raw material gas within the apparatus main body can be easily uniformized without uneven flow, and the This has the remarkable effect that an epitaxial film having a uniform thickness distribution is formed and contributes to improving the performance of IC devices such as CCDs.

Furthermore, by including a flow meter for measuring the amount of intake air in the control mechanism, the measured value of the amount of intake air can be adjusted to
It is possible to provide feedback as appropriate. In other words, by including the flow in measuring device in the control system, it is possible to always maintain a constant flow rate of the raw material gas introduced into the apparatus main body, and the flow rate of the raw material gas introduced into the apparatus main body is controlled. Fluctuations in flow rate can be prevented, and the pressure distribution within the device body can be easily made uniform.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing one embodiment of the present invention, and FIG.
The figure is a plan sectional view of FIG. 1, and FIG. 3 is a velocity distribution diagram showing a general velocity distribution within the main body of the apparatus.

Claims (2)

[Claims] (1) In a vapor phase growth apparatus in which a source gas is flowed in a substantially horizontal direction onto a wafer surface disposed in an apparatus main body to form an epitaxial film on the wafer surface, the susceptor on which the wafer is placed; A plurality of intake ports are provided on the wall of the main body of the apparatus between the source gas introduction hole and a plurality of pressure gauges for measuring pressure are provided on the wall opposite to the wall. A vapor phase growth apparatus, further comprising a control mechanism that controls the pressure within the apparatus main body based on measured values of the plurality of pressure gauges and is connected to the intake port. (2) The vapor phase growth apparatus according to claim 1, wherein the control mechanism includes a flow rate measuring device for measuring the amount of intake air.