JPH05283367A - Device for recovering normal pressure of air-tight chamber - Google Patents

Abstract

PURPOSE:To enable the door of an air-tight chamber to be opened favorably at recovery of normal pressure of an air-tight chamber by providing an air-tight chamber with a a pressure difference gauge which detects the relative pressure difference between the inside pressure of the air-tight chamber and the outside pressure of the chamber. CONSTITUTION:Load lock chambers 6 and 7 are provided with pressure difference gauges 30 and 31 which detect the pressure difference between the inside pressure of the load lock chambers 6 and 7 and the outside atmospheric pressure. Moreover, pressure sensors 32 and 33, which detect the absolute pressure inside the load lock chambers 6 and 7, are annexed to these pressure difference gauges 30 and 31. Each pressure difference gauge 30 and 31 is equipped with a pair of inlets for taking the specified atmosphere inside and outside the chamber into a gauge, and one inlet between these inlets in a pair are connected to the load lock chambers 6 and 7 via valves 34 and 35, and also the other inlet is opened to the air outside the load lock chambers 6 and 7. Accordingly, the pressure difference between the indoor side and the outdoor side can be detected accurately regardless of the fluctuation of the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atmospheric pressure restoring device for an airtight chamber.

[0002]

2. Description of the Related Art Vacuum processing and processing using an airtight chamber are variously performed in various devices. For example, in semiconductor manufacturing equipment, epitaxial growth, plasma CVD, LPCV
Vacuum processing is performed in various devices such as D, sputtering, reactive ion etching, vacuum deposition, ion implantation, ion beam application equipment, electron beam application equipment, and molecular beam epitaxy. According to vacuum processing, plasma discharge,
A physical or chemical phenomenon such as an electron beam or an ion beam can be appropriately generated, and the mean free path of the active species can be lengthened, and a strong directivity can be imparted to it. Further, in the treatment under the vacuum state, the treatment can be performed more uniformly than under the atmospheric pressure, and it contributes to lowering the temperature and improving the cleanliness.

Generally, such various vacuum processing apparatuses are provided with an airtight chamber, for example, a load lock chamber, for taking in or taking out an object to be processed in the vacuum processing chamber. The case where a load lock chamber is used as the airtight chamber will be described below. The load lock chamber allows the loading and unloading of objects to be processed without opening the vacuum processing chamber to the atmosphere.The load lock chamber is placed in front of or behind the vacuum processing chamber via a gate valve. Has been done. By the combined operation of the gate valve and the vacuum exhaust system operation, the vacuum exhaust of the load lock chamber and the normal pressure return are repeatedly performed, and the normal pressure inside the vacuum process chamber is returned even when the object to be processed is taken in or taken out. Various processes can be continued without any effort.

When the object to be treated is taken in and taken out through the load lock chamber before and after the vacuum treatment as described above, first, an inert gas such as N ₂ gas is supplied into the load lock chamber to load the load. The atmospheric pressure in the lock chamber is restored, and then the door of the load lock chamber is opened to transfer the objects to be processed. At this time, in order to know the end of the return of the load lock chamber to the normal pressure, pressure sensors such as a convextron and a pressure switch have been conventionally used to measure the pressure in the load lock chamber.

[0005]

However, in the above-mentioned pressure sensors such as the convectron and the pressure switch,
There is an improvement that the pressure in the load lock chamber cannot be measured with sufficiently high accuracy. In particular, when the external atmospheric pressure fluctuates due to various environments, an unexpected differential pressure is generated inside and outside the load lock chamber. When the door of the load lock chamber is opened with the unplanned pressure difference, an unplanned air flow is generated in the door opening, which causes dust particles (particles) to fly up. The processed material may be contaminated. There is also an improvement in that noise is generated due to airflow leakage when the door is opened. Such improvements are also the same in the normal pressure restoring device using an airtight chamber other than the load lock chamber.

[0006] The present invention, when returning to the normal pressure of the airtight chamber,
An object of the present invention is to provide a normal pressure restoring device for an airtight chamber, which is capable of simply and accurately detecting the pressure in the airtight chamber and satisfactorily opening the door of the airtight chamber.

[0007]

In order to achieve the above object, a normal pressure restoring device according to the present invention opens the inside of an airtight chamber which is maintained in a substantially vacuum state to the atmosphere so that the vacuum pressure of the airtight chamber is reduced. In a normal pressure restoration device that destroys and returns to almost atmospheric pressure,
The airtight chamber is provided with a differential pressure gauge for detecting a relative pressure difference between the indoor pressure and the outdoor pressure of the airtight chamber.

[0008]

In the means having such a structure, the differential pressure gauge detects the relative pressure difference between the inside and the outside of the airtight chamber, so that the pressure relationship between the inside and the outside is accurate regardless of the fluctuation of the external atmospheric pressure. It is well detected.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, an example in which the atmospheric pressure restoring device for an airtight chamber according to the present invention is applied to a plasma etching device will be described. As shown in FIG. 1, an airtight vacuum processing chamber 1
A parallel plate electrode 2 for etching is provided inside, and a vacuum pump 4 connected through an exhaust pipe 3
Is configured so that a predetermined processing vacuum state is achieved.

On both sides of the vacuum processing chamber 1, load-lock chambers 6 and 7 having airtightness along the transfer direction of the semiconductor wafer 28 as an object to be processed, gate valves 8, and gate valves 8 are provided.
9 are arranged side by side. The gate valves 8 and 9 perform opening and closing operations in an airtight manner, and by opening and closing the gate valves 8 and 9, the inside of the vacuum processing chamber 1 and the inside of the load lock chambers 6 and 7 are opened. Is airtightly configured to be able to communicate and close. Further, gate valves 10 and 11 for airtightly opening and closing are provided at the respective ends on the opposite side of the load lock chambers 6 and 7, and the load lock is performed by opening and closing the gate valves 10 and 11. The indoor sides of the chambers 6 and 7 are airtightly closed or open to the outdoor atmosphere.

Further, the sender 12 is arranged so as to face the gate valves 10 and 11 of the load lock chambers 6 and 7.
And the receiver 13 is arranged. These senders 1
A plurality of semiconductor wafers 28 as objects to be processed can be stored in the receiver 2 and the receiver 13. On the other hand, transfer arms 5, 5 for transferring the semiconductor wafer 28 are arranged inside the load lock chambers 6, 7.
Semiconductor wafer 28 stored in the sender 12
However, the semiconductor wafer 28 is taken in by the transfer arm 5 of the load lock chamber 6 or stored in the receiver 13 by the transfer arm 5 of the load lock chamber 7. Each gate valve 8, 9, 1 described above
0 and 11 are individually openable and closable so that the airtight state of each of the load lock chambers 6 and 7 and the vacuum processing chamber 1 is formed individually and opened individually. .

On one side wall of the load lock chambers 6 and 7,
Exhaust pipe 1 opening to the inside of the load lock chambers 6 and 7
6, 17 are connected. Each of these exhaust pipes 16, 17
Are connected to vacuum pumps 18 and 19, respectively, and air operation valves 14 and 15 that perform exhaust control in synchronization with the indoor operations of the load lock chambers 6 and 7, respectively, are provided in the middle thereof. ..

On the other hand, purge gas supply pipes 21 and 22 are connected to the opposite side walls of the load lock chambers 6 and 7. The purge gas supply pipes 21 and 22 are connected to the gas supply unit 20 by being connected to an integrated piping system. In addition, in the middle of each of these purge gas supply pipes 21 and 22,
Air operation valves 23 and 24 for controlling air supply in synchronization with the indoor operation of the load lock chambers 6 and 7 are provided, respectively, and downstream of the air operation valves 23 and 24, that is, the load lock chambers 6 and 7.
Side, needle valves 25, 26 for finely adjusting the gas flow rate
Is provided. The gas supply mechanism constituting these normal pressure recovery devices supplies a purge gas at a predetermined timing when the load lock chambers 6 and 7 are opened to the atmosphere, and the gas supply unit 20 supplies a clean gas such as a purge gas to the gas supply unit 20. Purified nitrogen gas is stored.

The exhaust pipes 16 and 17 and the purge gas supply pipes 21 and 22 are connected to each other in such a positional relationship that the clean gas introduced into the load lock chambers 6 and 7 at the time of opening to the atmosphere exists in the load lock chambers 6 and 7. The particles are removed on average, and the particles are not dropped onto the semiconductor wafer 28 (not shown) existing on the transfer arm 5. That is, as shown in FIGS. 2A and 2B, the exhaust pipes 16 and 17 are connected to the upper corners of the side walls 6a and 7a of the load lock chambers 6 and 7, respectively. , Purge gas supply pipe 2
Reference numerals 1 and 22 are connected to the corners of the bottom surfaces 6b and 7b, which are substantially diagonally related to the exhaust pipes 16 and 17, respectively. Therefore, the clean gas introduced into the chamber from the lower corner side by the purge gas supply pipes 21 and 22 almost uniformly passes through the load lock chambers 6 and 7 as indicated by an arrow A in FIG. Meanwhile, it is configured to be discharged from the exhaust pipes 16 and 17 in the upper corners.

The exhaust pipes 16 and 17 and the purge gas supply pipes 21 and 22 may be located in any diagonal positions as described above, for example, the side walls 6a and 7a to which the exhaust pipes 16 and 17 are attached. On the other hand, the purge gas supply pipes 21 and 22 may be configured to be attached to the lower corners of the opposite side walls 6c and 7c facing the purge gas supply pipes 21 and 22.

A filter 27 for enhancing the cleanliness of the supplied nitrogen gas is attached to the connection opening portions of the purge gas supply pipes 21 and 22 to the load lock chambers 6 and 7. The filter 27 is, for example, stainless steel (SUS).
It is formed of a sintered body.

Further, the load lock chambers 6 and 7 are provided with differential pressure gauges 30 and 31 for detecting a pressure difference between the pressure in the load lock chambers 6 and 7 and the external atmospheric pressure. Further, the differential pressure gauges 30 and 31 are respectively provided with pressure sensors 32 and 33 for detecting the absolute pressure in the load lock chambers 6 and 7. The differential pressure gauges 30 and 31 are
It has a pair of inlets for introducing the measured atmosphere inside and outside the room into the instrument, and one inlet of the pair of inlets is connected to the Claude Lock chambers 6 and 7 via valves 34 and 35, respectively. And the inlet on the other side is the load lock chamber 6,
It is open to each of the 7 outdoor atmospheres. As the differential pressure gauges 30 and 31 in this embodiment, a region near the atmospheric pressure, for example, 7
In the region around 00 Torr, a minute pressure, for example 0.01
The one that can measure pressure in units of Kg / cmm ² or less is used.

On the other hand, the pressure sensors 32 and 33 are constructed so as to measure the pressure only in the load lock chambers 6 and 7, and a convectron, a pressure switch or the like is adopted. The pressure sensors 32 and 33 have a relatively wide measurable range from vacuum to atmospheric pressure.
As described in the section of the prior art, the measurement accuracy is not so high, and only the absolute pressure in the load lock chambers 6 and 7 is measured regardless of the atmospheric pressure on the outdoor side.

The processing operation of the etching apparatus having such a structure will be described below. In the etching process, first, the semiconductor wafer 28 supplied from the sender 12
Are loaded into the load lock chamber 6, and prior to the loading of the semiconductor wafer 28, the normal pressure in the load lock chamber 6 is restored as follows.

First, the air operation valve 23 of the load lock chamber 6 which is maintained in a predetermined vacuum state is opened, and purging nitrogen gas is introduced into the load lock chamber 6 from the purge gas supply pipe 21. The amount of nitrogen gas introduced at this time depends on the exhaust capacity and the volume of the room,
A minute flow rate, for example, 2 to 6 liters / minute, is set in consideration of the time from the vacuum state to the atmospheric pressure state and the flow of particles. This is because if a large amount of this nitrogen gas for purging is supplied at once, the particles will wind up and cause contamination.

At the same time when the nitrogen gas for purging is introduced, the air operation valve 14 of the exhaust pipe 16
However, it is opened for several seconds, for example.
As a result, the nitrogen gas initially introduced is removed to the outside together with the particles remaining in the load lock chamber 6. When the removal of particles is completed, the air operation valve 14 of the exhaust pipe 16 is closed.

The nitrogen gas for purging continues to be continuously introduced into the load lock chamber 6 through the purge gas supply pipe 21, and the pressure in the load lock chamber 6 approaches the atmospheric pressure on the outdoor side. At this time, the pressure in the load lock chamber 6 from the vacuum state to the vicinity of the atmospheric pressure is first measured by the pressure sensor 3
4 is measured. The measurement by the pressure sensor 34 is to measure the pressure inside the load lock chamber 6 with relatively coarse accuracy, and also to measure the absolute pressure that is unrelated to the atmospheric pressure outside the room. Then, when the pressure in the load lock chamber 6 approaches the atmospheric pressure, the following measurement by the differential pressure gauge 30 is started.

That is, when the pressure in the load lock chamber 6 is increased to a region near atmospheric pressure, for example, a region around 700 Torr by the introduction of nitrogen gas for purging, the valve 3
2 is opened, and the atmosphere in the load lock chamber 6 is the differential pressure gauge 3
Introduced to zero. As a result, the differential pressure between the pressure inside the load lock chamber 6 and the atmospheric pressure, which is the pressure outside the load lock chamber 6, is accurately measured by the differential pressure gauge 30. The pressure in the load lock chamber 6 is, for example, 0.01 kg / cmm with respect to the atmospheric pressure.
^The above differential pressure gauge 30 shows that only a small pressure of ² or less has increased.
Purge gas supply pipe 21 in which the nitrogen gas for purging has been introduced into the load lock chamber 6 until then.
The air operation valve 23 is closed, and the return of the load lock chamber 6 to the normal pressure is completed.

When the differential pressure gauge 30 is used to measure the differential pressure between the inside and outside of the load lock chamber 6, the measurement can be performed with higher accuracy than the conventional pressure sensor, and each environment can be measured. Even if the outside air pressure fluctuates depending on the conditions, the relationship between the pressure difference between the inside and the outside of the load lock chamber 6 can always be set as planned.

When the return of the load lock chamber 6 to the normal pressure is completed as described above, the gate valve 1 of the load lock chamber 6 is completed.
0 is opened, but at this time, the relationship of the pressure difference between the inside and the outside of the load lock chamber 6 is maintained as the initial setting as described above. More specifically, in this embodiment, the pressure on the indoor side of the load lock chamber 6 is set higher than the atmospheric pressure on the outdoor side by a minute pressure. Therefore, when the gate valve 10 is opened, a very slight air flow is generated from the indoor side of the load lock chamber 6 toward the outdoor side, whereby dust particles (particles) are removed to the outdoor side and the gate valve 10 is opened. Generation of sound associated with opening 10 is minimized.

When the gate valve 10 is opened, the transfer arm 5 extends from the load lock chamber 6 through the gate valve 10, the semiconductor wafer 28 supplied from the sender 12 is gripped by the transfer arm 5, and the load lock is performed. It is taken into the chamber 6. At this time, as described above, the inside of the load lock chamber 6 is in the substantially atmospheric pressure state, which is the same as the outside pressure. Then, after the gate valve 10 is closed to make the load lock chamber 6 airtight, the load lock chamber 6 is closed.
The inside is evacuated to a vacuum degree lower than the vacuum degree of the vacuum processing chamber 1. Under this vacuum state, the semiconductor wafer 28
Are transferred into the vacuum processing chamber 1 through the gate valve 8. Load lock chamber 6 after gate valve 8 is closed
In the same manner as described above, the atmosphere is released, that is, the normal pressure is restored, and the next semiconductor wafer 28 is taken into the load lock chamber 6.

In the vacuum processing chamber 1 into which the semiconductor wafer 28 is loaded, the gate valve 8 is closed, and then the vacuum pump 4 rapidly evacuates the vacuum processing chamber 1 to maintain the inside of the vacuum processing chamber 1 at a predetermined vacuum degree. Then, in this vacuum processing chamber 1, a plasma etching process by high frequency power is performed. The semiconductor wafer 28 that has undergone the etching process is transferred to the load lock chamber 7 of a predetermined vacuum pressure while being held by the transfer arm 5 of the load lock chamber 7.

Next, the air operation valve 24 of the load lock chamber 7, which is kept in a predetermined vacuum state, is opened, and purging nitrogen gas is introduced into the load lock chamber 7 from the purge gas supply pipe 22. Simultaneously with the introduction of this purging nitrogen gas, the air operation valve 15 on the side of the exhaust pipe 17 is opened for, for example, several seconds, and the nitrogen gas initially introduced remains in the load lock chamber 7. Excluded outside with particles. When the particles are removed, the exhaust pipe 17
The air operation valve 15 is closed. The nitrogen gas for purging continues to be continuously introduced into the load lock chamber 7 through the purge gas supply pipe 22, and the pressure in the load lock chamber 7 approaches the atmospheric pressure on the outdoor side. At this time, the pressure in the load lock chamber 7 from the vacuum state to the vicinity of the atmospheric pressure is first measured by the pressure sensor 35. The measurement by the pressure sensor 35 is to measure the pressure in the load lock chamber 7 with relatively coarse accuracy, and to measure the absolute pressure that is unrelated to the atmospheric pressure outside the room.
When the pressure in the load lock chamber 7 approaches the atmospheric pressure, the measurement by the differential pressure gauge 31 is started.

That is, when the pressure in the load lock chamber 7 is brought to a region near the atmospheric pressure, for example, around 700 Torr by the introduction of nitrogen gas for purging, the valve 33 is opened and the pressure in the load lock chamber 7 is increased. The differential pressure gauge 31 starts highly accurate measurement of the differential pressure between the external pressure and the atmospheric pressure. The pressure in the load lock chamber 7, if that is higher by a small pressure, for example 0.01 kg / cmm ² or less with respect to the atmospheric pressure measured by the differential pressure gauge 31, purging the load lock chamber 7 until it The air operation valve 24 of the purge gas supply pipe 22 which has introduced the nitrogen gas for use is closed, and the return of the load lock chamber 7 to the normal pressure is completed.

When the differential pressure gauge 31 is used to measure the differential pressure inside and outside the load-lock chamber 7 as described above, it is possible to measure with higher accuracy than the conventional pressure sensor, and it is possible to measure the differential pressure depending on each environmental condition. Even when the atmospheric pressure fluctuates, the relationship between the pressure difference inside and outside the load lock chamber 7 can always be set as planned.

When the return to normal pressure of the load lock chamber 7 is completed as described above, the gate valve 1 of the load lock chamber 7 is completed.
1 is opened, and the semiconductor wafer 28 is transferred by the transfer arm 5.
Are carried out to the receiver 13.

In the present embodiment, since the pressure measurement is performed while using the pressure sensors 34 and 35 for the differential pressure gauges 30 and 31, the relative pressure in the load lock chambers 6 and 7 can be measured extremely smoothly. However, embodiments without a pressure sensor are possible.

Although the embodiments described above use the present invention in an etching apparatus, the present invention is not limited to this, and epitaxial growth, plasma CVD, LPC are possible.
VD, sputtering, reactive ion etching, vacuum deposition,
The same can be applied to devices such as ion implantation, ion beam applied devices, electron beam applied devices, molecular beam epitaxy, etc., and devices for handling objects such as semiconductor wafers and LCD substrates under various vacuums, and various other types. It can also be applied to all devices having an airtight chamber.

[0034]

As described above, according to the present invention, the pressure in the airtight chamber can be easily and accurately detected by the relative pressure with the outdoor atmospheric pressure. The pressure can be maintained at the planned pressure at all times,
It is possible to prevent dust particles (particles) from flying up when the door of the airtight chamber is opened to avoid contamination of the object to be processed, and to minimize the door opening noise caused by the air flow.

[Brief description of drawings]

FIG. 1 is a plan cross-sectional explanatory view showing the configuration of an etching apparatus to which the present invention is applied.

FIG. 2 is a side cross-sectional explanatory view and a plan cross-sectional explanatory view showing a configuration of a load lock chamber used in the device shown in FIG.

[Explanation of symbols]

 1 Vacuum processing chamber 6, 7 Load lock chamber 28 Semiconductor wafer 30, 31 Differential pressure gauge 34, 35 Pressure sensor

Claims (2)

[Claims] 1. A normal pressure restoration device for an airtight chamber, wherein the inside of the airtight chamber maintained in a substantially vacuum state is opened to the outdoor atmosphere to restore the atmospheric pressure of the airtight chamber to approximately atmospheric pressure. A normal pressure restoring device for an airtight chamber, wherein a pressure difference gauge for detecting a relative pressure difference between an inner pressure and an outer pressure of the airtight chamber is provided in the airtight chamber. 2. The normal pressure restoring device for an airtight chamber according to claim 1, wherein the differential pressure gauge is provided with a pressure sensor for detecting an absolute pressure in the airtight chamber from a vacuum pressure to a pressure near atmospheric pressure. A device for restoring normal pressure in an airtight chamber characterized by being