KR20070054765A - Method of creating a vacuum in a load lock chamber and apparatus for performing the same - Google Patents

Abstract

In a vacuum forming method of a load lock chamber, a first vacuum pressure is provided inside a load lock chamber containing a substrate to firstly exhaust gas present in the load lock chamber upwards. A second vacuum pressure higher than the first vacuum pressure is provided inside the load lock chamber to secondary exhaust the gas present in the load lock chamber, thereby forming the inside of the load lock chamber to the second vacuum pressure. This suppresses the problem that foreign matter is generated due to a sudden pressure change during vacuum formation of the load lock chamber or that foreign matter existing on the top of the load lock chamber is easily transferred onto the target substrate by vacuum evacuation.

Description

Method of creating a vacuum in a load lock chamber and apparatus for performing the same}

1 is a schematic configuration diagram illustrating a problem occurring when vacuum forming a load lock chamber according to the prior art.

2 is a schematic flowchart illustrating a vacuum forming method of a load lock chamber according to an embodiment of the present invention.

3 is a schematic diagram illustrating an apparatus suitable for carrying out the vacuum forming method of the load lock chamber described above.

Explanation of symbols on the main parts of the drawings

100: vacuum forming apparatus of the load lock chamber 110: load lock chamber

112: load lock door 114: slit door

116: cassette loader 120: main vacuum providing unit

122: vacuum pump 124: main exhaust line

125: first port 126: first opening and closing valve

130: auxiliary vacuum providing unit 134: auxiliary exhaust line

135: second port 136: second on-off valve

137: pressure control valve 138: diffuser (diffuser)

140: control unit C: cassette

W: Wafer

The present invention relates to a vacuum forming method of a load lock chamber and an apparatus for performing the same. More particularly, the present invention relates to a vacuum forming method of a loadlock chamber used in a facility for manufacturing a semiconductor device, and to an apparatus for performing the same.

Recently, the manufacturing technology of the semiconductor device has been developed in the direction of improving the degree of integration, reliability and response speed, etc. in order to meet various needs of consumers. Generally, a semiconductor device is manufactured by forming a predetermined film on a silicon wafer used as a semiconductor substrate and forming the film in a pattern having electrical properties.

The pattern is formed by a sequential or iterative process of various unit processes such as deposition, photolithography, etching, ion implantation, polishing, cleaning, drying for film formation. Most of the above unit processes are performed under high vacuum, in order to prevent the semiconductor substrate from contacting the outside air and to prevent foreign matter from adhering on the semiconductor substrate. Processing apparatuses for performing the unit processes generally include a load lock chamber for firstly accommodating a semiconductor substrate to block contact with external air in the process atmosphere.

The load lock chamber is connected to the process chamber in which the unit process is performed, and is maintained in a vacuum state while receiving the semiconductor substrates. This is to stably maintain the vacuum state of the process chamber, and to shorten the process progress time. When loading the semiconductor substrate into the process chamber or unloading the semiconductor substrate from the process chamber, a door connecting the process chamber and the load lock chamber or a door connecting the transfer chamber and the load lock chamber is opened.

At this time, if the internal pressure of the load lock chamber is different from the process chamber or the transfer chamber, the pressure of the process chamber or the transfer chamber should be changed to be the same as the load lock chamber. The loading and unloading of the semiconductor substrate may be performed by setting the internal pressure of the load lock chamber to be the same as the process chamber or the transfer chamber in order to avoid the need to change the pressure of the process chamber or the transfer chamber during loading and unloading of the semiconductor substrate. Time loss during unloading is prevented and contamination of the semiconductor substrate in the atmosphere is prevented.

FIG. 1 is a schematic configuration diagram illustrating a problem of a load lock chamber vacuum forming apparatus according to the related art. Referring to FIG. 1, a cassette C containing wafers W used as a semiconductor substrate is loaded. It is loaded into the load lock chamber 10 through the door 12. Contaminants P1 and P2 are attached to the load lock chamber 10 while the processing process for the wafers W is continued in the process chamber (not shown). The lower part of the load lock chamber 10 is provided with a vacuum providing unit 20 including a pump 22 and an exhaust line 24 connected through a port 16 formed on a bottom surface of the load lock chamber 10.

The pollutants P1 and P2 may fall downward due to a sudden pressure change when pumping by the vacuum providing unit 20 starts. In addition, due to the pressure change, as the temperature inside the load lock chamber 10 decreases, the gas present therein may be condensed and converted into a pollutant source. The contaminants generated in this way may be transferred to the front surface of the wafer W by the exhaust air flow formed downward by the pumping, which may cause a defect of the semiconductor device.

A first object of the present invention for solving the above problems is to prevent the rapid generation of pressure changes in the load lock chamber, while at the same time to suppress the transfer of contaminants in the load lock chamber onto the substrate It is to provide a vacuum forming method of the lock chamber.

It is also a second object of the present invention to provide an apparatus suitable for performing the vacuum forming method of the load lock chamber.

A vacuum forming method of a load lock chamber according to an aspect of the present invention for achieving the first object, first, by providing a first vacuum pressure inside the load lock chamber for receiving a substrate is present inside the load lock chamber The gas is first exhausted upwards. In addition, a second vacuum pressure higher than the first vacuum pressure is provided inside the load lock chamber to secondary exhaust the gas existing in the load lock chamber, thereby forming the inside of the load lock chamber at the second vacuum pressure. .

According to an embodiment of the present invention, the first vacuum pressure may be 150 to 300 Torr.

According to the above-described method, the load lock chamber is first formed at a first vacuum pressure lower than the second vacuum pressure as the buffer vacuum pressure before forming the second vacuum pressure as the reference vacuum pressure. That is, the internal pressure of the load lock chamber is prevented from rapidly decreasing to the second vacuum pressure. Accordingly, the sudden pressure change prevents the gas inside the load lock chamber from condensing and acting as a particle source on the semiconductor substrate. In addition, a gas flow is generated upward in the load lock chamber during the first exhaust, and contaminants such as foreign substances attached to the upper inner surface of the load lock chamber when the first vacuum is formed are lowered and transferred to the atmospheric substrate. Suppressed. Therefore, the yield and reliability of a semiconductor device can be improved.

A vacuum forming apparatus of a load lock chamber according to another aspect of the present invention for achieving the second object is connected to an upper portion of the load lock chamber for waiting a substrate and primary gas in the load lock chamber at a first vacuum pressure. And an auxiliary vacuum providing part for evacuating, and a main vacuum providing part for secondary evacuating the gas inside the load lock chamber in which the first vacuum pressure is formed to a second vacuum pressure higher than the first vacuum pressure.

According to another embodiment of the present invention, the main vacuum providing unit, the main vacuum providing unit, a vacuum pump for providing the second vacuum pressure, a main exhaust line connected from the pump to the lower portion of the load lock chamber, And an on / off valve installed on the main exhaust line. In this case, the auxiliary vacuum providing unit, the auxiliary exhaust line branched from the main exhaust line between the vacuum pump and the on-off valve and connected to the upper portion of the load lock chamber to form an air flow inside the load lock chamber upward, A diffuser is provided at the end of the auxiliary exhaust line connected to the top of the load lock chamber and distributes the exhaust flow and at the same time reduces the exhaust velocity, and a pressure installed in the auxiliary exhaust line and provided through the auxiliary exhaust line. It may include a pressure control valve for controlling to the first vacuum pressure. The diffuser is also positioned higher than the substrate waiting in the load lock chamber.

As described above, according to the apparatus, an auxiliary vacuum providing part for providing a buffer vacuum pressure to a main vacuum providing part for forming the inside of the load lock chamber as a vacuum can be easily implemented, thereby easily implementing the above-described method for forming the load lock chamber vacuum. Can be.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments and may be implemented in other forms. The embodiments introduced herein are provided to make the disclosure more complete and to fully convey the spirit and features of the invention to those skilled in the art. In the drawings, the thickness of each device or film (layer) and regions has been exaggerated for clarity of the invention, and each device may have various additional devices not described herein.

Vacuum forming method of load lock chamber

2 is a schematic flowchart illustrating a vacuum forming method of a load lock chamber according to an embodiment of the present invention.

First, a description will be given of the process generally performed before forming a vacuum in the load lock chamber. The load lock chamber is a space in which a processing substrate, such as a semiconductor substrate, on which a processing process is to be performed, is waiting in the processing chamber, and loads the processing substrate inside the load lock chamber. Here, when a predetermined vacuum is formed inside the load lock chamber before the loading is performed, it is preferable to form the inside of the load lock chamber at atmospheric pressure. This is because it is difficult to load the substrate to be processed by opening the load lock door in a vacuum formed state. For example, an atmospheric pressure may be formed by injecting a purge gas such as nitrogen gas (N ₂ ) into the load lock chamber.

The first vacuum pressure is provided inside the load lock chamber accommodating the substrate to be treated to first exhaust the gas present in the load lock chamber upwards (S10). Specifically, the first vacuum pressure is lower than a preset reference vacuum pressure (second vacuum pressure) to be formed in the load lock chamber. For example, the first vacuum pressure may be set to about 150 Torr to about 300 Torr. That is, the first vacuum pressure is a buffer vacuum pressure provided before forming the reference vacuum pressure.

Therefore, the phenomenon that the pollutant which was deposited on the inner wall of the load lock chamber at the time when the exhaust of the gas starts, is released from the chamber by the exhaust pressure is suppressed.

In addition, when a reference vacuum pressure is immediately formed without providing the buffer vacuum pressure, a sudden pressure change occurs and the temperature inside the load lock chamber is lowered, whereby the gas inside is condensed. The phenomenon of transition onto the substrate is suppressed.

On the other hand, it is preferable that the air flow of the gas exhausted by the first vacuum pressure is formed from the lower portion of the load lock chamber to the upper portion, that is, upward. Thereby, by raising the airflow of the gas, contaminants such as particles fall and can be suppressed from being transferred onto the front surface of the substrate. For reference, in the air in the load lock chamber, a portion where a pattern is formed on the substrate to be processed, that is, the front surface of the substrate is generally exposed upward. Therefore, the problem that the separated contaminants fall to act as a particle source to generate a process defect during the substrate processing process such as etching process is suppressed.

Subsequently, a second vacuum pressure higher than the first vacuum pressure is provided inside the load lock chamber to secondary exhaust the gas existing in the load lock chamber, thereby forming the inside of the load lock chamber to the second vacuum pressure. (S20). For example, the second vacuum pressure is a reference vacuum pressure to be formed in the load lock chamber, and the gas inside the load lock chamber may be provided to exhaust through the lower portion thereof. As such, when the gas is discharged downward, it may be stopped to provide the first vacuum pressure to the load lock chamber before providing the second vacuum pressure. This is because the airflow formed by the second vacuum pressure collides with the airflow formed in the first vacuum pressure, and a complicated airflow can be generated to drop contaminants attached to the inside of the load lock chamber.

As such, when the inside of the load lock chamber is formed at the reference vacuum pressure, it is possible to easily suppress the transfer of foreign substances to the substrate. In addition, a sudden pressure change occurs at the start of pumping the gas in the load lock chamber, in which a transition of the pollutant is mainly caused by out-gasing or temperature drop. Therefore, this problem can be solved by providing a buffer vacuum pressure (first vacuum pressure) smaller than the second vacuum pressure for forming the reference vacuum pressure before forming the load lock chamber to the reference vacuum pressure.

Load Lock Chamber Vacuum Forming Device

3 is a schematic diagram illustrating an apparatus suitable for carrying out the vacuum forming method of the load lock chamber described above.

Referring to FIG. 3, the apparatus 100 is connected to an upper portion of the load lock chamber 110, and an auxiliary vacuum unit for first exhausting the gas inside the load lock chamber 110 to a first vacuum pressure. The main vacuum providing unit 120 is configured to secondaryly exhaust the gas inside the load lock chamber 110 in which the first vacuum pressure is formed to a second vacuum pressure higher than the first vacuum pressure.

First, the load lock chamber 110 will be briefly described. The load lock chamber 110 may be directly connected to a process chamber (not shown) in which a process of processing a surface of a wafer W used as a semiconductor substrate is performed. It is connected via a transfer chamber. A load lock door 112 is provided at one side of the load lock chamber 110, and a slit door at the other side of the load lock chamber 110 connected to the process chamber or the transfer chamber. 114 is installed. The wafer W moves between the process chamber and the load lock chamber 110 through the slit door 114. A cassette loader 116 is provided in the load lock chamber 110 to support a cassette for accommodating a plurality of wafers W and to move the cassette. By the vertical movement of the cassette loader 116, the wafer W to be loaded into the process chamber or the transfer chamber may move in front of the slit door 114.

In the load lock chamber 110, a preset vacuum pressure (second vacuum pressure) required in the load lock chamber 110 is exhausted by exhausting (gas secondary) the gas existing in the main vacuum providing unit 120. Main vacuum providing unit 120 for providing is provided. In detail, the main vacuum providing unit 120 includes a first vacuum pump 122, a main exhaust line 124, and a first opening / closing valve 126. The first vacuum pump 122 is disposed at one side of the load lock chamber 110, and the main exhaust line 124 connected to the vacuum pump is formed at a lower portion of the load lock chamber 110. It may be connected to the load lock chamber 110 through. For example, the first port 125 is formed at the bottom of the load lock chamber 110, and the main exhaust line 124 communicates with the interior of the load lock chamber 110 through the bottom. The gas is exhausted downward. The first on-off valve 126 is installed on the main exhaust line 124.

In addition, before the main vacuum providing unit 120 provides the second vacuum pressure, the auxiliary vacuum providing unit 130 may provide a first vacuum pressure lower than the second vacuum pressure in the load lock chamber 110. ) Is provided. The auxiliary vacuum providing unit 130 provides a first vacuum pressure, ie, a buffer vacuum pressure, for suppressing a sudden change in the internal pressure of the load lock chamber 110 by the main vacuum providing unit 120. Perform the function. The auxiliary vacuum providing unit 130 may include a second vacuum pump, an auxiliary exhaust line 134, a diffuser 138 (diffuser) and a pressure control valve 137. Here, the auxiliary vacuum providing unit 130 shares the first vacuum pump 122 with the main vacuum providing unit 120 without having to include the second vacuum pump separately from the first vacuum pump 122. This is preferable because it is easy in terms of economics and in view of retrofit of the conventional apparatus.

In more detail, one end of the auxiliary exhaust line 134 is connected to the main exhaust line 124 between the first vacuum pump 122 and the first opening / closing valve 126, and the other end of the rod is connected to the rod. It is connected to the load lock chamber 110 through a second port 135 formed on the lock chamber 110. Here, the auxiliary vacuum providing unit 130 preferably evacuates the gas inside the load lock chamber 110 upward. This creates an exhaust air stream upward, whereby contaminants adhering to the inner side of the upper portion of the load lock chamber 110, etc., are released while the exhaust pressure starts to be provided, and the wafer is waiting inside the load lock chamber. To suppress falling onto the (W) s.

Therefore, an end portion of the auxiliary exhaust line 134 connected through the second port 135 is preferably disposed higher than the position of the uppermost substrate among the substrates waiting in the load lock chamber 110. For example, when the plurality of wafers W are waiting in the load lock chamber 110 while being accommodated in a cassette, the end of the auxiliary exhaust line 134 may have a cassette loader in the load lock chamber 110. When the cassette is seated on 116, it is positioned at a higher position than the cassette.

A diffuser 138 (diffuser) is installed at an end of the auxiliary exhaust line 134 that communicates through the top of the load lock chamber 110. The diffuser 138 distributes the exhaust flow in the load lock chamber 110, and at the same time, the exhaust velocity is to reduce the exhaust pressure by reducing the exhaust pressure of the auxiliary vacuum providing unit 130. Therefore, since the internal environment of the load lock chamber 110 such as pressure, temperature, etc. does not change suddenly, the state of the contaminants attached therein can be kept as stable as possible. As an example of the diffuser 138, it is suitable to be able to moderate the inflow rate of air and perform airflow dispersion appropriately, such as a diffuser laminated with porous ceramic layers having different particle sizes in cross section. On the other hand, the first vacuum pressure provided to the auxiliary vacuum providing unit 130 to act as a buffer is preferably about 150 Torr to 300 Torr.

The pressure control valve 137 and the second open / close valve 136 are provided on the auxiliary exhaust line 134. The pressure control valve 137 controls the second vacuum pressure provided by the vacuum pump to the first vacuum pressure, and the second open / close valve 136 opens and closes the auxiliary exhaust line 134. Since the auxiliary exhaust line 134 has a diameter much smaller than the diameter of the main exhaust line 124, the vacuum pressure provided to the load lock chamber 110 is changed by changing the cross-sectional area of the auxiliary exhaust line 134. It can be adjusted easily. For example, there is a needle valve as the pressure control valve 137.

The main vacuum providing unit 120 and the auxiliary vacuum providing unit 130 are connected to the control unit 140 for controlling the vacuum forming sequence of the load lock chamber 110 as described above. Specifically, the control unit 140 is connected to the first vacuum pump 122 and the first opening and closing valve 126 of the main vacuum providing unit 120, respectively, the second vacuum of the auxiliary vacuum providing unit 130 Respectively connected to the pump (if present), the second open / close valve 136 and the pressure control valve 137.

For example, in the vacuum forming process of the load lock chamber 110 according to the operation of the control unit 140, the control unit 140 first closes the first opening / closing valve 126 of the main vacuum providing unit 120 and simultaneously By opening the second open / close valve 136 of the auxiliary vacuum providing unit 130, the first vacuum pressure is provided to the inside of the load lock chamber 110 through the auxiliary exhaust line 134.

At this time, the controller 140 controls the pressure control valve 137 to lower the second vacuum pressure provided by the first vacuum pump 122 to the first vacuum pressure. Accordingly, residual gas inside the load lock chamber 110 begins to be first exhausted upward through the auxiliary exhaust line 134. In addition, the vacuum pressure may be lowered by the diffuser 138 provided at the end of the auxiliary exhaust line 134, and at the same time, the exhaust air flow upward may be dispersed.

When the pressure in the load lock chamber 110 is lowered to about 150 to 300 Torr, the first valve is turned off and a second vacuum pressure is provided in the load lock chamber 110. Accordingly, the gas remaining in the load lock chamber 110 is secondaryly exhausted downward through the main exhaust line 124 to thereby form the inside of the load lock chamber 110 at a second vacuum pressure, that is, a preset vacuum pressure. .

According to the embodiments of the present invention as described above, when the reference vacuum pressure is formed inside the load lock chamber, the pressure inside the chamber is gradually lowered, whereby contaminants are transferred onto the substrate to be processed in the load lock chamber. The phenomenon of transition can be suppressed. Therefore, the problem that the yield of the semiconductor device due to the pollutant is lowered can be solved.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (5)

Providing a first vacuum pressure inside the load lock chamber containing the substrate to first exhaust gas present therein upwards; And Providing a second vacuum pressure higher than the first vacuum pressure inside the load lock chamber to secondary exhaust the gas present in the load lock chamber, thereby forming the inside of the load lock chamber to the second vacuum pressure. A vacuum forming method of a load lock chamber comprising. The method of claim 1, wherein the first vacuum pressure is 150 to 300 Torr. An auxiliary vacuum providing portion connected to an upper portion of a load lock chamber for waiting a substrate and for first exhausting a gas in the load lock chamber to a first vacuum pressure; And And a main vacuum providing part for secondary exhausting the gas inside the load lock chamber in which the first vacuum pressure is formed to a second vacuum pressure higher than the first vacuum pressure. The method of claim 3, wherein the main vacuum providing unit, A pump for providing said second vacuum pressure; A main exhaust line from the pump to the bottom of the load lock chamber; And An on / off valve installed on the main exhaust line, The auxiliary vacuum providing unit, An auxiliary exhaust line branched from the main exhaust line between the pump and the on / off valve and connected to an upper portion of the load lock chamber to upwardly create an air flow inside the load lock chamber; A diffuser provided at an end of an auxiliary exhaust line connected to an upper portion of the load lock chamber for distributing exhaust flow and reducing exhaust velocity; And And a pressure control valve installed at the auxiliary exhaust line and configured to control the pressure provided through the auxiliary exhaust line to a first vacuum pressure. 5. The apparatus of claim 4, wherein the diffuser is disposed higher than the substrate waiting in the load lock chamber.

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