JPH01292825A - Low pressure preparation chamber apparatus - Google Patents

Abstract

PURPOSE:To obtain a low pressure preparation chamber with less residual foreign matter and contamination by foreign matter of materials such as wafer by constituting the gas outlet and gas inlet on a line in the plane in parallel with the upper surface of a sample and providing these inlet and outlet with the apertures thereof provided opposed to each other. CONSTITUTION:The gas outlet 4 and the gas inlet 3 are provided in such a manner that these are located on a line in the plane parallel to the upper surface of a sample and the apertures of these are provided opposed to each other. The gas outlet 4 and gas inlet 3 which are provided to form a line in a plane parallel to the upper surface of a sample such as wafer placed on the sample board as described above assure smooth flow, at the time of exhausting the gas or supply the gas to the low pressure preparation chamber, of the gas in the low pressure preparation chamber without any deviation even under the existence of volume and gas within the pipe in the exhaust side or those within the pipe of supply side and always cause the gas to flow in the constant direction even in the case of exhaustion or supply of gas. Thereby, the gas including splashed foreign matters quickly flows at the lower side of upper surface of sample.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reduced pressure preparation chamber apparatus, and particularly to a reduced pressure preparation chamber apparatus suitable for processing samples such as semiconductor element substrates.

[Conventional technology]

As a decompression preparation chamber device, for example, JP-A-60-2381
As described in No. 33, a small chamber connected to an external evacuation means is provided on one of the front or rear closing means for carrying in and out processed products in the processing chamber, and a valve is provided inside the chamber to close the processing chamber (vacuum). room)
Processed products can be transported in and out without exposing them to the atmosphere. Load-lock chambers are known. This device has an air supply port that supplies air into the room and returns it to atmospheric pressure, and an exhaust port that exhausts the room and brings it to the same pressure as the processing chamber (vacuum chamber). Supply air, return it to atmospheric pressure, and open it.
A sample such as a wafer is carried into the open load-lock chamber, the load-lock chamber is hermetically sealed again, and the chamber is evacuated to reduce the pressure.The load-lock chamber and processing chamber (vacuum chamber) are communicated with each other to remove the sample. The sample is transferred from the load-lock chamber to the processing chamber, processed in the processing chamber, and then transferred from the processing chamber through the load-lock chamber by reverse operation. The air supply port of the load lock chamber of this apparatus is installed horizontally above the top surface of a sample such as a wafer. The exhaust port is installed so as to face the back surface of the sample.

As another example, in Japanese Patent Application Laid-Open No. 60-250644, both the air supply port and the exhaust port are installed facing the same direction. In the device disclosed in JP-A No. 60-91642, an air supply port is installed horizontally toward the top surface of the sample, and two exhaust ports are installed facing each other toward the back surface of the sample.

The method disclosed in JP-A-62-181440 performs high-pressure purge from the upper surface of the wafer to create a vertical flow.

It transports particles from above to below.

[Problem to be solved by the invention]

In the depressurization preparation chamber in the above conventional technology, the position of the exhaust port and the position of the air supply port are determined by the relative positional relationship of the exhaust port and the air supply port with each other, and the position of the air supply port and the exhaust port and the top surface of the sample such as a wafer. The relationship is designed without any particular consideration. Generally, the exhaust port of the decompression preparation room.

It is connected to the exhaust pipe diameter, and a solenoid valve is installed in the middle of this pipe. Similarly, the air supply port of the decompression preparation chamber is connected to the air supply side piping system, and a solenoid valve is also installed in the middle of this piping. Therefore, between the above exhaust port and the exhaust side solenoid valve.

And there must be a certain volume between the air supply port and the exhaust side solenoid valve.When exhausting the decompression preparation chamber, the exhaust side solenoid valve is opened and the supply side solenoid valve is closed.
Exhaust is carried out simultaneously within the depressurization preparation chamber and also within the air supply side piping system from the air supply port to the air supply side solenoid valve. Conversely, when supplying air to the decompression preparation chamber, the air supply side solenoid valve is opened and the exhaust side solenoid valve is closed, so that the air is supplied into the decompression preparation chamber and simultaneously into the exhaust side piping system from the exhaust port to the exhaust port solenoid valve. This means that they are also doing so. Therefore, in fact, the shape of the gas flow that occurs in the depressurization preparation chamber during both exhaust and air supply is determined by the internal volume of the exhaust side piping system, the internal gas, the internal volume of the air supply side exhaust pipe system, and the presence of the internal gas. It must be taken into consideration that the relative positions of the exhaust port and the air supply port are affected by the relative positions of the exhaust port and the air supply port. The actual situation is that this setting is made based on the design of the equipment outside the depressurization preparation room, without any consideration given to the gas flow that occurs during the decompression preparation room.

For this reason, if the relative positions of the exhaust port and the air supply port are inappropriate, the gas flow that occurs during exhaust and air supply will be uneven, with a large swirl inside the decompression preparation chamber.
There are places in the preliminary chamber where the flow direction is reversed during exhaust and air supply.

Therefore, if the flow contains foreign matter for some reason.

Due to this biased gas flow, the gas is not discharged quickly, but instead crosses the top surface of the wafer or other sample before being discharged, which results in the wafer or other sample being contaminated by foreign matter, which reduces yield. was there. In addition, due to the uneven flow and the flow whose direction is reversed during exhaust and air supply, there are places where foreign matter gets stuck, resulting in a wide area where foreign matter remains in a part of the decompression preparation chamber. There is also a problem in that the accumulation of these substances causes further contamination of the wafer.

Especially in single-wafer type decompression preparation chambers, which are expected to become more popular in the future, because they are single-wafer type.

In such a case, the volume inside the decompression preparation chamber becomes smaller.
Since the volumes of the exhaust side piping system and the air supply side piping system are relatively the same, the imbalance in the gas flow in the depressurization preparation chamber during exhaust and air supply as described above becomes significant, and the wafer There was also the problem that the sample was easily contaminated.

Note that in conventional depressurization preparation chamber devices, the air supply port and exhaust port are often installed above the top surface of a sample such as a wafer, and the exhaust port is installed below the depressurization preparation chamber.
Directly flowing the gas from the upper surface of the sample also has the problem of affecting the contamination of the sample with foreign matter.

In other words, in the conventional technology, the relative positions of both the exhaust port and the air supply port are set without any consideration being given to the effect that this will have on the gas flow that occurs during supply and exhaust. , foreign particles remain in the room,
There is a problem in that the flow of gas containing foreign matter crosses the top surface of a sample such as a wafer, contaminating the sample with foreign matter.

The present invention is based on the above-mentioned considerations, and an object of the present invention is to provide a depressurization preparation chamber that does not cause uneven gas flows during exhaust and gas supply, and is free from residual foreign matter and foreign matter contamination of materials such as wafers.

[Means to solve the problem]

For the above purpose, a vacuum preparation chamber is provided in a part of the vacuum processing chamber to carry samples into and out of the processing chamber.

The decompression preparation room is a decompression preparation room that includes a wall that defines a room, a sample support that moves within the room, an exhaust port for lowering the air pressure in the room, and an air supply port for increasing the air pressure. , the exhaust port and the air supply port are installed so that the exhaust port and the air supply port are arranged on a straight line in a plane parallel to the upper surface of the sample, and an opening of the exhaust port portion, By arranging the openings of the air supply ports to face each other.

achieved.

[Effect]

Exhaust ports and air supply ports that are installed to form a straight line in a plane parallel to the top surface of a sample such as a wafer installed on a sample stage are generated when evacuating or supplying air to the decompression preparation chamber. , the flow of gas in the decompression preparation chamber is determined by the volume and gas inside the exhaust side piping system and the volume and gas inside the air supply side piping system.
Even in the presence of gas, the flow is made to flow unbiased, and the flow of gas is always made to flow in the same direction, whether in the case of exhaust or air supply.

For this reason, even when foreign matter that exists in the vacuum preparation chamber due to adhesion to the wall surface of the vacuum preparation chamber is scattered by the gas flow generated by exhaust or supply air and flows with the gas, Even if there is no bias in the flow of gas in the room, and even if the gas flow contains scattered foreign objects,
Since the sample is discharged from the exhaust port without coming close to the upper surface of the sample such as the wafer, contamination of the sample such as the wafer with foreign matter is greatly reduced. At the same time, the gas flow that occurs during exhaust and air supply is not biased, and both exhaust and air supply always flow in one direction, and there is no place in the room where the flow is reversed between exhaust and air supply, so it is possible to reduce pressure. Foreign matter will not remain in the preparation room and will be promptly discharged outside.

(Example〕 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In this embodiment, the depressurization preparation chamber is a load lock chamber in semiconductor manufacturing equipment, and is a movable chamber to which a part of the drive unit is connected. An airtight chamber is formed by an upper outer wall 1 and a lower outer wall 2 having a sample support such as a wafer W in a part thereof. The gas inside the airtight room is exhausted to the outside through the exhaust port 3, and clean gas is supplied through the air supply port 4. The exhaust port 4 is connected to the outside of the load lock room through an exhaust side piping system to an exhaust mechanism including a vacuum pump. A valve and a solenoid valve 6 are installed in this exhaust side piping system, and the exhaust flow rate can be adjusted by the valve.

The solenoid valve 6 is opened when exhausting air, and closed when air is being supplied. Further, the air supply port 4 is connected to a mechanism for supplying clean gas to the outside of the load lock chamber via an air supply side piping system. A valve and a solenoid valve 7 are also installed in this air supply side piping system, and the air supply flow rate can be adjusted by the valve. The solenoid valve 7 in the air supply side piping system is opened when air is supplied, and closed when air is exhausted.

The wafer W is installed on a wafer installation stand 5.

The air supply port 4 and the exhaust port 3 are arranged in a straight line in a plane in which the center of the opening of the air supply port 4 and the center of the opening of the exhaust port 3 are parallel to the upper surface of the wafer W installed on the wafer installation table 5. It is installed so as to constitute the intake air 4 opening part and the exhaust 3 opening part,
They are placed facing each other.

As described above, when evacuating the load lock chamber, the air supply side solenoid valve 7 is closed, the exhaust side solenoid valve 6 is opened, and the inside of the load lock chamber is evacuated by the exhaust mechanism. When supplying clean gas into the load lock chamber, the solenoid valve 6 on the exhaust side is closed, the solenoid valve 7 on the air supply side is opened, and the clean gas supply mechanism supplies gas into the load lock chamber. Therefore, at the time of exhaust, the gas in the air supply side piping system from the air supply side electromagnetic valve 7 to the air supply port 4 is also exhausted at the same time as the gas in the load lock chamber. A portion of the gas in the air supply side piping system flows into the load lock chamber through the air supply port 4, passes through the load lock chamber, and is discharged to the outside through the exhaust port 3. Similarly, when supplying air.

The supplied gas passes through the load-lock chamber and flows from the exhaust-side solenoid valve 6 to the exhaust-side piping system leading to the exhaust port 3, as in the load-lock chamber.

Conventionally, when designing a load lock chamber, the existence of piping systems on the air supply side and the exhaust side and the influence of internal gas on the flow of gas that occurs when supplying and exhausting the load lock chamber were not considered at all. However, as described above, the presence of the air supply and exhaust side piping systems and the presence of internal gas affect the flow during supply and exhaust in the load lock chamber, and significantly affect the contamination of wafers with foreign substances. In this example, we investigated how far the foreign matter in the load lock chamber moves and how much it remains after the chamber is evacuated and air supplied once, as shown in Fig. 5(a). (b), θ is the angle formed by the air supply port and the exhaust port in the circumferential direction. In this experiment, foreign particles were intentionally attached to arbitrary locations in the load lock chamber, and how the attached position moved and how much remained after each exhaust and supply were recorded. It is something. In this embodiment, although some amount is present near the exhaust port, the amount is very small.

If the air supply port and the exhaust port are set at relative positions other than those in this example, a larger amount of foreign particles will remain in the load lock chamber over a wider area than in this example. In addition, the flow that occurs during supply and exhaust is also thought to have a biased shape, as if swirling inside the room. Furthermore, it is thought that there will be places in the room where the flow is reversed during air supply and air exhaust, resulting in an increase in foreign matter contamination of wafers.

Let's consider the causes of these phenomena. As described above, during exhaust, gas in the air supply side piping system flows into the load lock chamber from the air supply port, passes through the load lock chamber, and is discharged from the exhaust port. When supplying air, the supplied gas flows not only into the load-lock chamber but also through the exhaust port and into the exhaust piping system. Therefore, if the relative positions of the air supply port and exhaust port in the load-lock chamber are not appropriate, the supply gas will・The gas flow generated during exhaust becomes stagnant in the room or becomes uneven as it swirls around the room. Foreign particles adhering to the walls of the load lock chamber are scattered by the force of the gas, but at this time, if the gas flow is unbalanced, the "dirty" gas containing foreign particles will swirl around the top surface of the wafer. flows to For this reason, foreign matter easily adheres to the wafer and causes contamination, and due to the unevenness of the flow, a large amount of foreign matter remains in the load lock without being promptly discharged. In addition to the imbalance of gas, the fact that there are places where the direction of flow during air supply and air exhaust is reversed is also a cause of the large residual amount. For the above-mentioned reasons, it is thought that these trends can be observed almost at any relative position.

However, as in this embodiment (θ=180°), the center of the exhaust port opening and the center of the air supply port are installed so that they form a straight line in a plane parallel to the top surface of the wafer, and the opening are installed opposite each other, the presence of the supply and exhaust piping systems has no effect on the flow shape within the load lock chamber.

Therefore, both during exhaust and air supply, the gas flow is always axially symmetrical with respect to the straight line connecting the center of the exhaust port opening and the center of the air supply port opening, so it does not stagnate or swirl inside the room. There is no, and the gas flow is always unidirectional, both during exhaust and air supply. For this reason, the scattered foreign particles do not come close to the upper surface of the wafer and are promptly discharged from the exhaust port, so that the wafer is not contaminated and the number of foreign particles remaining in the load lock chamber is greatly reduced.

From the above experimental results and considerations, compared to the conventional load-lock chamber, in this example, the shape of the gas flow is always axially symmetrical with respect to the straight line formed by the air supply and exhaust ports, and the wafer installation table is Since it flows in one direction from the side, that is, below the top surface of the wafer, it efficiently discharges foreign particles that could contaminate the wafer without bringing them close to the wafer.

It is clear that the load-lock chamber is characterized by being extremely effective in reducing foreign-matter contamination of wafers by eliminating as much foreign matter as possible from remaining in the load-lock chamber.

Note that a similar effect is expected if θ=180'±10°.

As another example, as shown in Fig. 3, the opening cross-sectional area of the exhaust port is made larger than that of the air supply port, and the cross-sectional area of the piping outside from the exhaust port is gradually reduced. , there is one in which the piping is passed downward through the lower outer wall. With this configuration, the gas flow generated during supply and exhaust will flow quickly without stagnation or uneven circulation inside the load lock chamber, so foreign objects on the wall will be removed by the force of the gas. Even if it scatters, it is difficult to adhere to the wafer. Furthermore, with such a configuration, even if a small amount of foreign matter remains, the remaining area will be moved further away from the wafer and will eventually be evacuated.

Very effective in reducing wafer contamination.

In addition, the air supply port of the load lock chamber according to conventional technology is often installed above the top surface of the wafer, facing toward the wafer. However, if the air supply port is located in this position, foreign matter is likely to adhere to the wafer. Therefore, no effect can be expected in reducing wafer contamination.Therefore, it is considered that this embodiment is more effective in reducing wafer contamination.

〔Effect of the invention〕

According to the present invention, the gas flow inside the decompression preparation chamber that occurs when air is supplied and exhausted from the decompression preparation chamber is divided into the volume and gas inside the air supply side piping system installed outside the decompression preparation chamber and the exhaust side piping system. The flow is not biased even by the internal volume or the presence of gas; that is, the gas flows axially symmetrically with respect to the straight line connecting the exhaust port and the air supply port. Moreover, at the same time, the gas flow always flows in a fixed direction, whether in the case of air supply or exhaust, and there is no place where the gas flow is reversed between air supply and exhaust.

For these reasons, for example, even if foreign matter that has adhered to the wall of the decompression preparation chamber for some reason is scattered due to the fluid force of the gas generated during supply and exhaust, the flow of gas containing the scattered foreign matter will not reach the decompression preparation chamber. It quickly flows below the top surface of the sample, such as a wafer, without crossing the top surface of the sample. In addition, the flow does not swirl or deviate, but rather flows in an axially symmetrical shape to the axis connecting the air supply and exhaust ports, so that in the decompression preparation chamber, there are no particles of foreign matter. Large residual amount and wide residual area do not occur.

Foreign particles are promptly discharged outside the decompression preparation chamber.

In addition, there is no point where the direction of gas flow is reversed during air supply and exhaust, and the gas always flows in one direction both during air supply and exhaust, so foreign substances can be removed quickly. Since the foreign particles are gathered toward the exhaust port side and discharged from the exhaust port to the outside of the depressurization preparation chamber, it is possible to prevent a large amount of foreign particles from remaining in a wide area.

Furthermore, in order to achieve a shorter throughput than currently possible, the volume of the depressurization preparation chamber is expected to be reduced in the future, so the relative volume of the supply-side piping system and the exhaust-side piping system volume will be is larger than the volume of the depressurization preparation chamber, and the relative position of the air supply port and exhaust port will further affect the gas flow generated in the decompression preparation chamber, which is thought to have a negative effect on foreign matter adhesion and contamination of samples such as wafers. . However, with the present invention, the volume of the piping system basically does not affect the shape of the flow, so
The cleanliness of samples such as wafers can be maintained. For similar reasons,
Even if the volume of the piping system increases due to design, the present invention still does not affect the shape of the flow in the depressurization preparation chamber, so the cleanliness of samples such as wafers can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
It is a view taken along the ■-■ arrow in the figure. FIG. 3 is a sectional view showing another embodiment of the present invention, and FIG. 4 is a view taken along the line I'V-rV in FIG. FIGS. 5(a) and 5(b) are diagrams showing the results of an experiment on the movement and residual state of foreign particles using an embodiment of the present invention. 1... Upper outer wall, 2... Lower outer wall, 3... Air supply port, 4... Exhaust port, 5... Wafer installation stand, 6... Air supply side solenoid valve, Figure 1 Wire 2 Figure 4--One air supply port W-One-Wafer Figure 4

Claims (1)

[Claims] 1. A depressurization preparation chamber provided in a part of a vacuum processing chamber for transporting samples into and out of the processing chamber, which includes walls forming the chamber, a sample support stand that moves within the chamber, and a vacuum preparation chamber for transporting samples into and out of the processing chamber. In the decompression preparation chamber, the exhaust port and the air supply port are arranged in a straight line in a plane parallel to the upper surface of the sample, and A depressurization preparation chamber device, characterized in that the exhaust port and the air supply port are installed so that the exhaust port and the air supply port are located opposite each other.