JPH05291144A - Chemical vapor deposition equipment and its vaporiser - Google Patents

Abstract

PURPOSE:To stabilize the concentration of reaction gas when the reaction gas is generated by bubbling with a carbureter, and supplied to a reaction chamber in a chemical vapor deposition equipment. CONSTITUTION:A valve 20a installed in a reaction gas introducing tube 6b just before a reaction chamber 1: a bypass 21 reaching an exhaust tube 8 is installed in the reaction gas introducing tube in front of the valve 20a; a valve 20b is installed in the middle part of the bypass 21; babbling of small flow rate is performed when a film is not formed; the valve 20a on the reaction chamber side is closed; the valve 20b on the bypass side is opened; the reaction gas is made to flow toward the exhaust tube 8 side via the bypass 23; bubbling of set amount is performed just before a film is formed; the valve 20b on the bypass side is closed; the valve 20a on the reaction chamber side is opened; the reaction gas is supplied to the reaction chamber 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical vapor deposition apparatus used in a semiconductor manufacturing process and its vaporizer,
In particular, the present invention relates to a method for forming a film on a semiconductor wafer by using a gas obtained by vaporizing an alcoholate (salt of metal and alcohol) liquid reaction material that is liquid at room temperature.

[0002]

2. Description of the Related Art In recent years, alcoholate, which is a liquid at room temperature, has been used to improve step coverage in semiconductor manufacturing processes.
A thin film is formed on a semiconductor wafer using a gas obtained by vaporizing a (metal salt and alcohol salt) liquid reaction material. Since the formed thin film has different film thickness and properties depending on the concentration of the vaporized gas, a chemical vapor deposition apparatus capable of supplying a gas having a stable concentration is required.

A reaction gas supply system of a conventional chemical vapor deposition apparatus is constructed as shown in FIG. Hereinafter, tetraethoxysilane [Si is used as an alcoholate-based liquid reaction material.
(OC ₂ H5) ₄ ; hereinafter referred to as TEOS],
The case where nitrogen gas is used as the bubbling gas and ozone gas is used as the gas that reacts with TEOS will be described.
In FIG. 5, 1 is a reaction chamber for forming a film on a semiconductor wafer (not shown), and 2 is an oxygen gas C from the oxygen gas introducing pipe 3a.
Is an ozone generator for converting a part of the ozone into ozone and supplying it to the reaction chamber 1 through the ozone introducing pipe 3b. 4a, 4b,
4c is a vaporizer, 4a is for TEOS gas generation, 4b
Is for generating a gas containing phosphorus, and 4c is for generating a gas containing boron. Vaporizer 4
Cylinders 5a, 5b and 5c filled with a liquid material for generating a desired gas are housed in a, 4b and 4c, respectively. 6a is nitrogen gas B which is a bubbling gas
A nitrogen gas introduction pipe for introducing the gas, 6b is a vaporizer 4a,
Reaction gas introduction pipes for supplying the reaction gases from 4b and 4c to the reaction chamber 1, 7 is a flow rate controller for controlling the flow rates of the gases from the oxygen gas introduction pipe 3a and the nitrogen gas introduction pipe 6a, and 8 is the reaction An exhaust pipe for exhausting the finished gas from the reaction chamber 1, and a heater 9 for preventing vaporized gas from being reliquefied.

In the chemical vapor deposition apparatus constructed as described above, a predetermined amount of ozone gas introduced from the ozone inlet tube 3b onto a semiconductor wafer (not shown) heated to a high temperature in the reaction chamber 1 reacts with the same. A reaction product film is formed on the semiconductor wafer by reacting a certain amount of the reaction gas (TEOS gas, gas containing phosphorus and boron) supplied from the gas introduction pipe 6b.

FIG. 6 is a diagram showing the structure of the vaporizer 4a.
9 is a heater wound around the tank 5 to keep the temperature of the tank 5 constant, 6a is a nitrogen gas introducing pipe for introducing the nitrogen gas B which is a bubbling gas, and 6c is TEO.
A bubbling tube for bubbling nitrogen gas B into S liquid A, and 6b is a vaporized T mixed with nitrogen gas.
Outlet pipe for guiding EOS gas to the reaction chamber 1, 10, 11, 12
Is a valve for opening and closing each gas pipe.

Next, the operation of the vaporizer 4a will be described.
The TEOS liquid A is put in the tank 5, and the TEOS liquid A in the tank 5 is heated and maintained at a constant temperature by the heater 9,
Nitrogen gas B is blown into the EOS liquid A through the bubbling pipe 6c to bubble the EOS liquid A. The TEOS liquid A vaporizes into the nitrogen gas B in contact with it, and vaporizes until the partial pressure becomes equal to the vapor pressure of the TEOS liquid A at that time,
Saturate when they are equal. If the nitrogen gas B and the TEOS gas are sufficiently saturated, the TEOS gas is generated according to the temperature of the TEOS liquid A and the amount of the bubbling nitrogen gas B at that time. Then, the TEOS gas is mixed with the nitrogen gas B and introduced into the reaction chamber 1 through the outlet pipe 6b. In the reaction chamber 1, the TEOS gas and ozone gas react with each other to form a reaction product film on the semiconductor wafer.

[0007]

The conventional chemical vapor deposition apparatus and the vaporizer thereof are constructed as described above, and the tank 5 is heated and maintained at a constant temperature by the heater 9. When vaporizing TEOS liquid A by bubbling,
The valve 10 is closed, the valves 11 and 12 are opened, and the N ₂ gas B is supplied from the bubbling pipe 6c to the TEOS liquid A in the tank 5.
The TEOS liquid A is vaporized by bubbling by blowing it into. In this case, TEOS solution A, the vapor pressure determined by the temperature and pressure, may vaporize into N ₂ space D to saturation is equal to the partial pressure of TEOS gas N ₂ space D.
The TEOS gas vaporized into the N ₂ space D flows out of the tank 5 through the reaction gas introduction pipe 6b together with the N ₂ gas B used for bubbling.

Next, when the TEOS liquid A is not vaporized in the vaporizer, the valve 10 is opened and the valves 11 and 12 are opened.
Is closed, and N ₂ gas B is passed through the bubbling pipe 6c and not into the tank 5 but into the reaction gas introduction pipe 6b. At this time,
The tank 5 is in a sealed state because the valves 11 and 12 are closed, and the bubbling pipe 6c to the N
_{2 Even if the} gas B is not bubbled into the TEOS liquid A, the TEOS liquid A is transferred from the surface of the TEOS liquid A to the N ₂ space D.
Will vaporize. When the period is not performed vaporization followed by the bubbling, state TEOS gas to N ₂ space D is gradually vaporized TEOS until saturation, during N ₂ space D to N ₂ gas and TEOS gas are mixed Becomes

In the above state, the valve 10 is closed,
Open valves 11 and 12 and bubbling pipe 6c to N ₂
When the TEOS liquid A is vaporized by bubbling the gas B, the TEOS gas vaporized by bubbling the N ₂ gas B and the TEOS liquid A vaporized in the N ₂ space D from the reaction gas introducing pipe 6b during a period when the vaporization by the bubbling is not performed. TEOS
Gas flows out at the same time. This state continues for a while until the TEOS gas in the N ₂ space D has flowed out.

That is, in the above-mentioned conventional chemical vapor deposition apparatus, the sequence of supplying the reaction gas is such that the bubbling is started immediately before the thin film formation and the TEOS liquid gasified by the bubbling is passed through the reaction gas introducing pipe 6b. Since it is designed to be supplied to the reaction chamber 1, TE by bubbling
For some time after the start of vaporization of the OS liquid A, TEOS gas vaporized by bubbling and N ₂ before the bubbling start
TEOS gas and reaction gas introduction pipe 6 saturated in the space D
The residual gas of b is simultaneously supplied to the reaction chamber 1 through the reaction gas introduction pipe 6b. Therefore, as shown in FIG.
For a while after the start of vaporization, the concentration of the TEOS gas generated from the reaction gas introduction pipe 6b is high and is not constant. In FIG. 7, the vertical axis represents the concentration of TEOS gas in the reaction gas introducing pipe 6b, and the horizontal axis represents time, showing changes in the TEOS concentration generated from the start of bubbling.

The present invention has been made in order to solve the above problems, and eliminates the initial gas saturated in the tank and the gas remaining in the pipe, and a gas having a stable concentration even at the start of bubbling. A chemical vapor deposition apparatus and a vaporizer for supplying the same.

[0012]

In the chemical vapor deposition apparatus according to the present invention, a valve is provided in the reaction gas introduction pipe immediately before the reaction chamber, and a bypass leading to the exhaust pipe is provided in the reaction gas introduction pipe in front of the valve. Install a valve in the middle of the bypass, bubbling at a small flow rate when film formation is not in progress, close the valve on the reaction chamber side and open the bypass side valve, let flow through the bypass to the exhaust pipe side, and start film formation Immediately before, bubbling of a set amount was performed, the bypass side valve was closed and the reaction chamber side valve was opened to supply the reaction chamber.

The vaporizer according to the present invention comprises a container for containing a liquid, a heater for heating and raising the temperature of the container to keep it at a constant temperature, and a container in which the liquid is immersed in the liquid and a gas is blown into the liquid. A gas blowing tube for vaporizing the liquid,
A pipe provided with a gas that is not immersed in the liquid and vaporized by the liquid and goes out of the container, and a pipe that is not immersed in the liquid and is a pipe that blows gas into the container in addition to the gas blowing pipe. Is.

[0014]

In the chemical vapor deposition apparatus of the present invention, the reaction gas introduction pipe immediately before the reaction chamber is provided with a bypass leading to the exhaust pipe, and bubbling is performed even when film formation is not performed, though a small amount is used for bubbling. As a result, the reaction gas introduced by the remaining reaction gas introduction pipe 6b and the reaction gas saturated by other than bubbling existing in the N ₂ space in the gas tank can be exhausted.

One of the two gas blowing pipes in the vaporizer of the present invention is immersed in the liquid, and the other is not immersed in the liquid. When vaporizing the liquid, it is immersed in the liquid. The gas is blown into the liquid from the gas blowing pipe and the liquid is vaporized by bubbling.When the liquid is not vaporized, the gas is not immersed in the liquid and the gas is put above the liquid in the container from the other gas blowing pipe. The vaporized gas, which is vaporized from the liquid surface while not being bubbled by being blown, is made to flow out from the container.

[0016]

【Example】

Example 1. FIG. 1 is a block diagram showing an embodiment of the invention of a chemical vapor deposition apparatus according to the present application. In the figure, 1 is CV
D Reaction chamber for film formation, 2 ozone generator, 3a oxygen gas inlet pipe, 3b ozone inlet pipe, 4a, 4b, 4c T
Vaporizers for EOS gas generation, gas generation containing phosphorus, and gas generation containing boron, 5a, 5b, 5c are cylinders filled with a liquid material, 6a is a nitrogen gas introduction pipe, 6
b is a reaction gas introduction pipe, 7 is a flow controller, 8 is an exhaust pipe, 9 is a heater, B is nitrogen gas, and C is oxygen gas, which are the same as those shown in FIG. The difference from the conventional example shown in FIG. 5 is that a bypass 21 leading to the exhaust pipe 8 is provided near the entrance of the reaction chamber 1 in the middle path of the reaction gas introduction pipe 6b, and vaporized gas is kept under a certain condition. It is configured to flow to the exhaust pipe 8. Further, vaporized gas is supplied to the reaction chamber 1 side and the exhaust pipe 8 to the reaction gas introduction pipe 6b and the bypass 21, respectively.
Valves 20a and 20b for switching to the side are provided.

FIG. 2 is a diagram showing each operation of the vaporized gas supply flow in the chemical vapor deposition apparatus of the above embodiment.

Next, the film forming operation in the above apparatus will be described. As shown in FIG. 2, when the thin film formation is stopped, the valve 20a is closed and the valve 20b is opened. Then, a small amount of bubbling is performed in the vaporizer 4, and the vaporized gas generated there flows through the pipe 6b and the bypass 21 to the exhaust pipe 8 and is exhausted. Immediately before forming the thin film, a bubbling operation of a set amount is performed in the vaporizer to open the valve 20a and close the valve 20b. Then, the reaction gas generated in the vaporizer 4 is introduced into the reaction chamber 1. That is, TEOS that was initially unstable
By the series of operations in which the gas concentration is as described above, the gas has a stable concentration even in the initial stage of film formation, and the film formation operation is also stabilized.

Example 2. FIG. 3 is a block diagram showing an embodiment of the invention of the vaporizer according to the present application. In the figure, the difference from the conventional example shown in FIG. 6 is that the purge pipe 6d from the N ₂ gas introduction pipe 6a via the valve 13 is connected to the TE in the tank 5.
That is, it was connected to the N ₂ space D that was not immersed in the OS liquid A. The other structure is similar to that of the conventional example shown in FIG.

Next, the operation of the vaporizer will be described. The tank 5 is heated and maintained at a constant temperature by the heater 9, and when the TEOS liquid A is vaporized by bubbling, the valves 10 and 13 are closed, the valves 11 and 12 are opened, and the N ₂ gas B is bubbled through the bubbling pipe 6c. Bubbling by blowing it into the TEOS liquid A in the tank 5 from TE
The OS liquid A is vaporized. At this time, TEOS liquid A has a vapor pressure determined by its temperature and pressure in TEOS of N ₂ space D.
It can vaporize into the N ₂ space until it equals the partial pressure of the gas and is saturated. The TEOS gas vaporized into the N ₂ space D exits from the tank 5 together with the N ₂ gas B used for bubbling, and is introduced into the reaction chamber through the reaction gas introduction pipe 6b.

Next, when the TEOS liquid A is not vaporized in the vaporizer, the valves 10 and 11 are closed and the valve 12 is closed.
And 13 and open the N ₂ inside the tank 5 through the purge pipe 6d.
The N ₂ gas B is blown into the space D. At this time, the TEOS gas vaporizing from the liquid surface of the TEOS liquid A to the N ₂ space D is caused by the flow of the N ₂ gas B from the purge pipe 6d to the reaction gas introducing pipe 6b, and the tank 5 from the reaction gas introducing pipe 6d.
Drained from.

As described above, even when the TEOS liquid A is not vaporized in the vaporizer, the tank 5 is not closed, and the TEOS liquid A is vaporized from the liquid surface of the TEOS liquid A by the flow of the N ₂ gas B. Gas is N ₂ space D above tank 5
Since it does not collect in TEOS liquid A
The amount of TEOS gas generated after the start of vaporization does not become unstable, and a certain amount of TEOS gas is maintained during bubbling.
OS gas can be generated stably.

Example 3. In the second embodiment, a purge pipe is provided from the N ₂ gas introduction pipe 6a to the tank 5 via the valve 11, and the N ₂ gas B is introduced into the reaction gas introduction pipe 6b.
As shown in FIG. 4, the N ₂ gas introducing pipe 16a independent of the N ₂ gas introducing pipe 6a and its valve 14 are provided, and the reaction gas introducing pipe 16b independent of the reaction gas introducing pipe 6b is provided. Is provided through the valve 15, and when the TEOS liquid A is not vaporized by bubbling, the valve 1
You may open 4 and 15 and let N ₂ (nitrogen) gas B flow into the N ₂ space D.

Other Embodiments. Examples (Examples 1, 2 and 3)
In the above, the TEOS liquid A was used as the liquid material and the N ₂ gas B was used as the bubbling gas, but a liquid having a similar function such as tetramethoxysilane (TMOS) instead of TEOS and He gas instead of the N ₂ gas. Materials and gases may be used. Further, it goes without saying that the shapes and arrangements of the tanks, the respective pipes and the like shown in the above embodiment are not limited to those described above.

[0025]

As described above, according to the invention of the chemical vapor deposition apparatus, a valve is provided immediately before the reaction chamber and a bypass leading to the exhaust pipe is provided in front of the reaction chamber, and a small amount of bubbling is always performed to allow the reaction. By exhausting the gas through the bypass to the exhaust pipe side, bubbling a set amount during film formation and supplying the gas to the reaction chamber, there is an effect that a stable concentration of vaporized gas can be obtained from the time when film formation is started.

Further, according to the invention of the vaporizer, the container in which the liquid is provided, which is provided with a heater for heating and raising the temperature and keeping it at a constant temperature, is immersed in the liquid in the container, and gas is contained in the liquid. By blowing, a gas blowing pipe that vaporizes the liquid, a pipe that is not immersed in the liquid, the vaporized gas of the liquid goes out of the container, and a gas blowing pipe that is not immersed in the liquid Separately, it is provided with a pipe for blowing gas into the container, and while the gas is blown into the liquid from the gas blowing pipe immersed in the liquid and bubbling is not performed to vaporize the liquid, the liquid The gas was blown into the upper part of the liquid in the container from a gas blowing pipe that was not immersed in it, and the vaporized gas that had evaporated from the liquid surface was allowed to flow out of the container while bubbling was not performed. Yo While the liquid is not vaporized, the gas vaporized by the liquid does not accumulate in the container, so the amount of vaporized gas generated after bubbling does not become unstable and the bubbling does not occur. While performing, there is an effect that a certain amount of vaporized gas can be stably generated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a reaction gas supply system showing an embodiment of a chemical vapor deposition apparatus according to the present invention.

FIG. 2 is a diagram for explaining a film forming operation of the above embodiment.

FIG. 3 is a sectional view showing an embodiment of a vaporizer according to the present invention.

FIG. 4 is a cross-sectional view of essential parts showing another embodiment of the vaporizer according to the present invention.

FIG. 5 is a cross-sectional view showing a configuration of a reaction gas supply system of a conventional chemical vapor deposition apparatus.

FIG. 6 is a sectional view showing a conventional vaporizer.

FIG. 7 is a graph showing a conventional reaction gas concentration.

[Explanation of symbols]

1 reaction chamber 4a, b, c vaporizer 5 tank 6a N ₂ gas inlet tube 6b reaction gas inlet tube 6c bubbling pipe 6d purge pipe 8 exhaust pipe 9 heaters 10-13 valves 20a reaction chamber side valve 20b bypass side valve 21 Bypass A TEOS liquid B N ₂ gas D N ₂ space

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toru Yamaguchi 4-1-1 Mizuhara, Itami-shi Kita-Itami Works, Ltd. (72) Inventor Akasa Yuki 8-1-1 Tsukaguchihonmachi, Amagasaki Mitsubishi Electric Corporation Company Central Research Institute (72) Inventor Takaaki Kawahara 8-1-1 Tsukaguchihonmachi, Amagasaki City Mitsubishi Electric Corporation Central Research Institute

Claims (2)

[Claims] 1. A chemical vapor deposition apparatus having a reaction gas supply system for supplying a gas to a liquid material in a vaporizer by bubbling a gas to vaporize the liquid material to generate a reaction gas and supplying the reaction gas to a reaction chamber. In, in the middle of the reaction gas introduction pipe from the vaporizer to the reaction chamber, provide a bypass to the exhaust side,
When not forming a film, bubbling with a small flow rate in the vaporizer was made to flow through the bypass to the exhaust side, and immediately before the start of film formation, a set amount of bubbling was made to be supplied to the reaction chamber. Chemical vapor deposition equipment. 2. A vaporizer used in a chemical vapor deposition apparatus, comprising a container for containing a liquid, and heating and heating the container,
A heater that keeps a constant temperature, a gas blowing pipe that is immersed in the liquid and blows gas into the liquid to vaporize the liquid, and a gas blowing pipe that is not immersed in the liquid and that is the upper part of the container. A vaporizer provided with a pipe for blowing gas into the space and a pipe for vaporizing the liquid, which is not soaked in the liquid and goes out of the container.