JPH04293778A - Discharge device for cvd device - Google Patents

Abstract

PURPOSE:To eliminate the formation of solid powder by the reaction of gaseous raw materials sent from a discharge pipe with air in the juncture of a discharge pipe for venting or a discharge main pipe for purging of the CVD device. CONSTITUTION:This device is constituted by forming a bulging discharge pipe connecting port 32 on the side wall of the discharge main pipe, connecting discharge pipes 26, 27, 28 for purging and the discharge pipe 8 for venting to the side wall of this port 32 and further, introducing an inert gas from the front end of the port while the purging or vent gas is sent from these discharge pipes to the above-mentioned port.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is based on the chemical vapor deposition method (
Chemical Vapor Depositio
Regarding the exhaust equipment for the equipment (hereinafter referred to as CVD equipment) for forming an insulating film etc. on the wafer surface by n), the vent exhaust of the CVD reaction chamber (hereinafter referred to as the CVD chamber) or the supply gas to the above chamber. When the purge exhaust gas from the purge flow regulator (commonly known as mass flow) flows into the exhaust main pipe, solid matter generated by the reaction blocks the exhaust pipe connection to the exhaust main pipe, causing the exhaust gas to This relates to improvements that do not cause a decrease in efficiency.

0002

[Prior Art and Problems to be Solved] For example, when forming a phosphosilicate glass film on a silicon wafer by plasma CVD, a CVD chamber contains silane (SiH4) and phosphine (P) as source gases.
In addition to introducing H4) and nitrogen oxide (N2O) gas, the wafer loaded in the chamber is heated by a heater, the pressure in the chamber is brought to a predetermined vacuum pressure, and a voltage is applied between the electrodes in the chamber. to turn the gas into plasma. Then, a phosphosilicate glass film is formed on the wafer surface by chemical vapor deposition.

[0003] The raw material gases such as silane, phosphine, and nitrogen oxide are introduced into the chamber through a flow rate regulator commonly called a mass flow, with the flow rate thereof being regulated. By the way, in order to carry out the wafers that have been subjected to vapor phase growth of phosphosilicate glass and to carry in new wafers, the CVD chamber is operated with nitrogen gas after each vapor phase growth process is finished, with suction by the vacuum pump stopped. The pressure inside the chamber is raised by the introduction, and at the same time, the chamber vent valve is opened to send out the above-mentioned raw material gas remaining in the chamber from the chamber as vent exhaust.

On the other hand, the above-mentioned flow rate regulator is also used to control the source gas at an accurate flow rate for each vapor phase growth treatment cycle.
In order to be able to feed nitrogen gas into the D chamber, after each vapor phase growth process, nitrogen gas is fed from a route different from the introduction route for the raw material gas, and also through an exhaust pipe that is different from the introduction route to the chamber. A purge process is performed to send out the remaining raw material gas. During the purging process of the chamber vent or each flow rate regulator, the above-mentioned raw material gas such as silane, phosphine, or nitrogen oxide is sent to the exhaust main pipe through the exhaust pipe.

[0005] Conventionally, the exhaust pipes from each of the flow rate regulators or chambers described above were simply connected to a large-diameter exhaust main pipe. This main exhaust pipe is basically open to the atmosphere at one end, so the above-mentioned silane, phosphine, or nitrogen oxide gas pushed out by nitrogen gas as a purge gas or vent gas enters the main exhaust pipe. When flowing into the exhaust pipe, these raw material gases react with the air in the exhaust main pipe to produce solid powder such as silica (SiO2) or phosphorus pentoxide (P4O10). Such solid powder adheres and accumulates in the vicinity of the outlet opening of each exhaust pipe to the main exhaust pipe, causing the problem that each exhaust pipe gradually becomes clogged. In this way, each flow regulator or CVD
It is clear that if a blockage occurs at the connection of the exhaust pipe from the chamber to the main exhaust pipe, a problem will arise in which the above-mentioned purge process or chamber vent process cannot be carried out smoothly.

The present invention was devised under the above-mentioned circumstances, and in a CVD apparatus, an exhaust pipe from a flow rate regulator interposed in a raw material gas supply line or an exhaust pipe from a CVD chamber. The purpose of this invention is to prevent the pipe from being blocked by solid matter produced by the reaction of raw material gas with air, by means of a simple structure.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention takes the following technical measures. That is, the present invention is an exhaust device for venting or purging exhaust of a CVD chamber and/or a flow rate regulator for supply gas to the chamber, wherein an exhaust pipe connection port is bulged on the side wall of a main exhaust pipe. At the same time, exhaust pipes from the CVD chamber and/or the flow rate regulator are connected to the side walls of the port, and an inert gas is introduced into the port from the portion to which the exhaust pipes are connected. It is characterized by connecting pipes.

[0008]

Effects and Effects of the Invention When purging the flow rate regulator for raw material gas or venting a CVD chamber, the inert gas is sent from the inert gas introduction pipe to the port formed in the exhaust main pipe. The tank is filled with an inert gas such as nitrogen gas. Therefore, it is difficult for air to exist inside this port. Therefore, the residual raw material gas sent into the port from each exhaust pipe by the purge exhaust or vent exhaust does not come into contact with air at the moment it is introduced into the port from each exhaust pipe, and these raw material gases No chemical reactions occur to form solid powders. The above exhaust gas that has passed through the port will eventually come into contact with the air in the exhaust main pipe and cause a reaction, but the point at which this reaction occurs is when it enters the exhaust main pipe. Even if solid powder is generated by contact, this solid powder will not be deposited on the opening of each exhaust pipe into the port.

Therefore, according to the exhaust system for a CVD apparatus of the present invention, a bulging port is formed in the exhaust main pipe, each exhaust pipe is connected to this port, and the inside of this port is made free. By filling the active gas with a simple configuration, the exhaust pipe leading from these to the exhaust main pipe can be used to prevent the flow between the raw material gas and air when venting the CVD chamber or purging the raw material gas flow rate regulator. The problem of gradual occlusion by solid powder caused by catalytic reactions is eliminated, and the pumping efficiency is kept stable for a long time.

[0010] Note that the inert gas introduction pipe to be connected to the above port may be one for feeding nitrogen gas. Nitrogen gas is already used as a venting gas in the CVD chamber or as a purge gas in each flow rate controller, and piping also exists, so it is also possible to introduce such nitrogen gas to the appropriate part of the above port through the piping. It can be done easily.

[0011]

[Description of Embodiment] An embodiment of the present invention will be specifically described below with reference to the drawings. Figure 1 shows plasma CVD
This is an example of an apparatus for chemical vapor phase growth of phosphosilicate glass on a wafer by a method. Code 1 is CV
A D chamber is shown in which a heater 2 for heating a plurality of wafers to be processed to a predetermined temperature is arranged. A wafer is usually carried into the CVD chamber 1 while being placed on a support base called a susceptor. Several types of pipes are connected to this CVD chamber 1. The first is a vacuum exhaust pipe 3 for creating a vacuum inside the chamber. This vacuum exhaust pipe 3 is connected to a vacuum pump 5 via an on-off valve 4, and the exhaust from the vacuum pump 5 is discharged via a pump exhaust pipe 6 to an exhaust main pipe 7 that collects the exhaust from the CVD apparatus as a whole. be done.

The second pipe connected to the CVD chamber 1 is a chamber vent exhaust pipe 8. This vent exhaust pipe 8 has an on-off valve 9 in its intermediate portion, and is connected to the exhaust main pipe 7. The third pipe connected to the CVD chamber 1 is a nitrogen gas supply pipe 10 for venting. This venting nitrogen gas supply pipe 10 is connected from a nitrogen supply source 11 to an appropriate part of the CVD chamber 1 via an on-off valve 12 . The fourth pipe connected to the CVD chamber 1 is a raw material gas supply pipe 13. In this example, silane (SiH4), phosphine (P
H4 ) and nitrogen oxide (N2 O) are used, the CVD chamber is equipped with a raw material gas supply pipe 13 that merges the outlet pipes of the flow rate regulators 14, 15, and 16 provided individually for these raw material gases. Connected to 1.

The source gas pipes leading to the flow rate regulators 14, 15, 16 are provided with on-off valves 17, 18, 19, respectively. Further, the outlet pipes of the flow rate regulators 14, 15, 16 are also provided with on-off valves 20, 21, 22, respectively. Furthermore, a piping configuration for purging the flow rate regulators 14, 15, 16 with nitrogen gas is added. That is, three pipes branched from the nitrogen gas supply pipe 10 are joined to each raw material gas pipe via on-off valves 23, 24, 25, and each flow rate regulator 14, 15
, 16 are respectively purge exhaust pipes 26, 27, 2.
8 are branched, and these purge exhaust pipes 26, 27
, 28 are connected to the exhaust main pipe 7. Note that opening/closing valves 29, 30, and 31 are also interposed at the base ends of the purge exhaust pipes 26, 27, and 28, respectively.

In the present invention, the vent exhaust pipe 8 and the purge exhaust pipes 26, 27,
28 is not directly connected to the exhaust main pipe as in the conventional case, but has a special connection structure as follows. That is, as shown in detail in FIG. 2, on the side wall of the large-diameter exhaust main pipe 7,
Exhaust pipe connection port 32 that bulges out into a cylindrical shape with a relatively small diameter.
On the other hand, the vent exhaust pipe 8 and each purge exhaust pipe 26, 27, 28 are connected to the side wall of this port 32, and a nitrogen pipe as an inert gas introduction pipe is connected to the top of this port 32. A gas introduction pipe 33 is connected thereto.

This nitrogen gas introduction pipe 33 may be connected to the nitrogen supply source 11, and preferably introduces nitrogen gas into the port 32 only when venting the chamber or purging the flow rate regulator. A valve device (not shown) is provided for this purpose. The most suitable position for providing the nitrogen gas introduction pipe 33 is on the distal side of the connection part of each exhaust pipe at the port 32. In this embodiment, the nitrogen gas introduction pipe 33 is connected to the distal end surface of the port 32, but it may be connected to the side wall of the port as long as it is on the distal end side of each of the exhaust pipe connection parts.

When the CVD apparatus is in the chemical vapor phase growth mode of phosphosilicate glass on a wafer carried into the CVD chamber, the pressure inside the chamber is reduced to a predetermined pressure by the vacuum pump 5, and the source gas supply pipe 1 is
3, a raw material gas mixture whose flow rate is adjusted to a predetermined value by flow rate regulators 14, 15, and 16 is introduced into the chamber. This raw material gas is turned into plasma by an interelectrode discharge (not shown), and a part of the raw material gas in the plasma state adheres to the wafer surface, and a thin film of phosphosilicate glass is formed on the wafer surface through chemical vapor deposition. It is formed.

[0017] When the chemical vapor deposition mode is finished, the pressure inside the chamber is increased and chamber venting is performed to vent the raw material gas remaining inside the chamber. At this time, valve 2
By closing all of 0, 21, and 22, the supply of raw material gas into the chamber is stopped, and by switching the valve 4 to close and stopping the vacuum pump 5, evacuation of the chamber 1 is stopped. Nitrogen gas from the gas supply pipe 10 is introduced into the chamber by opening the on-off valve 12. Furthermore, by opening the valve 9, the vent gas in the chamber 1 is sent out to the exhaust pipe port 32 or the exhaust main pipe 7 via the vent exhaust pipe 8.

[0018] Simultaneously with, or before or after, the chamber venting, a flow rate regulator purge is performed to wipe out the residual raw material gas inside the flow rate regulators 14, 15, and 16. At this time, the valves 17, 18, 19 of each raw material gas pipe leading to each flow rate regulator 14, 15, 16 are closed,
By opening the valves 23, 24, 25 of the purge nitrogen gas supply pipe branching from the nitrogen gas supply pipe 10, nitrogen gas is introduced into each flow rate regulator 14, 15, 16, and the flow rate regulator By opening the valves 29, 30, and 31, the purge exhaust gas that has passed through the ports 14, 15, and 16 is sent to the exhaust pipe connection port 32 or the exhaust main pipe 7 via each purge exhaust pipe 26, 27, and 28. Sent out.

While the purge exhaust or vent exhaust is introduced into the exhaust pipe connecting port 32 through the exhaust pipes 8, 26, 27, and 28 in this manner, the exhaust pipe connecting port 3
Nitrogen gas, which is an inert gas, is blown in from a nitrogen gas inlet pipe 33 connected to the tip of the inert gas.

As mentioned above, each exhaust pipe 8, 26, 27,
28 is an exhaust pipe connection port 3 which is not directly connected to the side wall of the exhaust main pipe 7 as in the conventional case, but whose inside is filled with inert nitrogen gas from the nitrogen gas introduction pipe 33.
2, the inside of the chamber 1 or each flow rate regulator 14 that is pushed out by nitrogen gas as a purge gas or vent gas.
, 15, 16 will not react with air and produce solid powder as soon as it is introduced into the exhaust pipe connection port 32. Therefore, according to the present invention, the connecting portion of the purge exhaust pipes 26, 27, 28 or the vent exhaust pipe 8 to the main exhaust pipe 7 is blocked by solid matter caused by the reaction of the residual raw material gas with air as described above. This effectively avoids problems such as. As a result, according to the present invention, the problem that the chamber venting or the purge efficiency of each flow rate regulator decreases over time is solved.

Of course, the scope of the invention is not limited to the embodiments described above. The CVD apparatus of the embodiment uses silane, phosphine, and nitrogen oxide as source gases to grow phosphosilicate glass on a wafer in a chemical vapor phase by plasma CVD. There are various other types of thin films to be grown, and accordingly, the gases or combinations thereof selected as source gases also vary. In short, the present invention is applicable to any type of CVD apparatus that vents or purges the CVD chamber of the CVD apparatus and the flow rate regulator used for supplying source gas. can do.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram schematically showing an example of a CVD apparatus employing the present invention.

FIG. 2 is a detailed diagram showing a configuration example of an exhaust pipe connection port that is a main part of the present invention or each exhaust pipe connected to the port.

[Explanation of symbols]

1 CVD chamber 8 Vent exhaust pipe 14, 15, 16 Flow rate regulator 26, 27, 28 Purge exhaust pipe 32 Exhaust pipe connection port 33 Nitrogen gas introduction pipe

Claims (1)

[Claims] 1. An exhaust device for venting or purging a CVD chamber and/or a flow rate regulator for gas supplied to the chamber, the exhaust device comprising a port for connecting an exhaust pipe formed in a bulge on a side wall of a main exhaust pipe. On the other hand, exhaust pipes from the CVD chamber and/or the flow rate regulator are respectively connected to the side walls of the ports, and on the distal side of the portions of the ports to which the exhaust pipes are connected,
CVD characterized by connecting an inert gas introduction pipe
Exhaust system for equipment.