JP4439140B2 - Semiconductor wafer processing equipment with dustproof function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that dust can be easily generated at a downstream apart from a fan when a door is opened by the differential pressure of the inside, since an air current being generated by the fan in a processing unit differs in currents of an upstream near the fan and a downstream in a method for preventing contamination of wafers, by leaving a clearance for preventing the dust from entering the inside from the outside even if a port for taking in and out the wafers is blocked by the door in a semiconductor wafer processing unit. SOLUTION: The problem is solved by the wafer processing unit where a first clearance for connecting the inside of a processing unit with the outside remains even if a port for taking in and out wafers is closed by a door, and clearance at an upstream of the main current of air is made larger than that of a downstream side in the first clearance.

Description

[0001]
BACKGROUND OF THE INVENTION
This invention has a higher degree of cleanliness when receiving and processing a wafer from a clean box for storing a semiconductor wafer (hereinafter referred to as a wafer) in a manufacturing process for semiconductors, electronic component-related products, optical disks, etc. The present invention relates to a wafer processing apparatus having a dustproof function.
[0002]
[Prior art]
Manufacture of wafers used for semiconductor devices and the like must be performed in an environment in which high cleanliness is guaranteed, and is generally performed in a so-called clean room in which the entire room is maintained at high cleanliness. . However, to keep the entire room, which occupies a large volume, at a high level of cleanliness, a large capital investment and maintenance cost are required. It was uneconomical because it required investment. Therefore, in recent years, the entire room has been kept highly clean by keeping the microenvironment space (hereinafter referred to as the mini-environment section) inside the processing apparatus highly clean without keeping the entire room highly clean. There are many techniques for obtaining the same effect as time (hereinafter, such a processing apparatus is called a clean apparatus).
That is, the clean device is laid out in a room where the manufacturing is performed, and the wafer storage container (hereinafter referred to as a clean box) in which the interior is kept highly clean is transferred between the clean devices, and dust enters from the outside. If you connect the clean box to the specified wafer loading / unloading port provided in the clean device and transfer the wafer through this wafer loading / unloading port, the cleanliness of the room where the production is performed is not increased. All the environments to which the wafer is exposed can be kept clean. As a result, it is possible to obtain the same effect as when the entire room is converted into a clean room, and it is possible to reduce the capital investment and maintenance costs and realize an efficient production process.
[0003]
In the clean apparatus as described above, a fan filter unit (referred to as a fan in this specification) is provided above the mini environment part in order to keep the mini environment part at a high cleanliness. This fan feeds clean air to the inside from the strainer with a filter incorporating air containing external dust and the internal pressure and external pressure (if P _a, typically the P _a is atmospheric pressure ) To increase the pressure (P _a + ΔP) higher than the outside by a predetermined pressure (ΔP). As a result, an air flow from the upper side to the lower side is generated inside the mini-environment portion, and further, this air flow generates an air flow from the inside of the mini-environment portion to the outside at the lower portion of the mini-environment portion. With this air flow, clean air can be discharged to the outside and the air flow from the outside can be cut off. As a result, contamination from outside can be prevented. Furthermore, it has been considered that if the mini-environment part is sealed as much as possible except when the wafer to be processed is taken in and out, it is possible to prevent the entry of dust from the outside and to obtain a higher cleanliness. It was. Therefore, the external environment and the mini-environment part are completely sealed by a door that closes the wafer loading / unloading port except when the wafer loading / unloading port provided in the clean box is connected to the clean box at the time of wafer transfer. .
[0004]
However, when the wafer is not delivered, the mini-environment part is isolated from the outside, so that the wafer inside is always kept at a high level of cleanliness. When opened, the differential pressure ΔP inside and outside the mini-environment generates an air flow that flows from the inside of the mini-environment to the outside, causing the following problems.
As described above, it is inevitable that the door is opened and an air flow is generated as long as the inside of the mini-environment is pressurized. However, in the conventional apparatus, the differential pressure ΔP at the moment of opening the door is particularly large, and a certain amount of time is required. The flow rate was larger than that in the case of the air flow generated by the differential pressure ΔP after the passage, and there was a greater disturbance.
On the other hand, the pressure in the clean box is almost atmospheric pressure, and when the air flow with disturbance is generated at the wafer loading / unloading port, a phenomenon occurs in which the clean box entrains the air flow inside. Since the external dust is agitated by the air flow flowing out of the wafer loading / unloading port, the air flow entrained in the clean box contains dust, resulting in wafer contamination and adversely affecting the quality of the wafer.
[0005]
In view of this, the mini-environment part is not completely sealed from the external environment by the door that closes the wafer loading / unloading port, but conversely, a method is conceivable in which the door is closed by a slight gap to close the wafer loading / unloading port. In other words, even when the door closes the wafer entrance / exit, the air flow from the inside of the mini-environment part to the outside works effectively, and there is a gap that prevents dust from entering the inside of the mini-environment part. It is intended to remain on the periphery of the door. As a result, even when the door is opened, the air flow accompanied by disturbance at the wafer loading / unloading port can be reduced to prevent wafer contamination.
[0006]
[Problems to be solved by the invention]
The method of providing such a gap produces a certain effect to prevent contamination of the wafer due to air flow disturbance, but has the following problems in order to completely prevent contamination of the wafer.
Inside the mini-environment part, an air flow is generated from the upper side to the lower side of the mini-environment part by a fan that takes in external air. This air flow is fast on the upstream side near the fan and gradually slows away from the fan and going downstream. Therefore, even if a gap is left around the door when the door closes the entrance / exit of the wafer as described above, the speed of the air flow near the upstream gap near the fan and the downstream side away from the fan There is a difference with the speed of the airflow near the gap. In general, the static pressure at the point of fast air flow is lower than the static pressure at the point of slow air flow. That is, in the mini-environment portion, the internal and external differential pressure ΔP in the vicinity of the upstream gap near the fan is smaller than the internal and external differential pressure ΔP in the vicinity of the downstream clearance away from the fan. Therefore, the disturbance generated when opening the door that closes the wafer entrance / exit is more likely to occur as the differential pressure increases, so the downstream gap away from the fan is larger than the upstream gap closer to the fan. Disturbance occurs. As a result, contamination of the wafer due to disturbance is more likely to occur in the upstream gap closer to the fan than the downstream gap away from the fan, and there is a problem that the dust-proof function of the downstream gap away from the fan is lowered.
[0007]
In addition, it is necessary to fix the clean box when a wafer is taken in and out of the mini environment part from the clean box. In the wafer processing apparatus, a docking plate is arranged to fix the clean box at a predetermined position. The clean box is placed on the docking plate, and wafers are taken in and out. The docking plate is disposed on the load port.
When the door is opened and the wafer loading / unloading port is opened, an air flow is generated from the inside of the mini-environment part to the outside. However, since the load port table has a certain size, the load port table has a certain size. The flow of the air flow is obstructed, and the speed of the air flow below the clean box with the docking plate becomes slower than the speed of the air flow above the clean box without the docking plate. This effect also affects the inside of the mini-environment part, and the clearance on the lower side of the clean box (downstream side away from the fan) compared to the air flow speed above the clean box (downstream side away from the fan). This causes a problem that the speed of the air flow becomes slow. In particular, a decrease in the speed of the air flow at the lower part of the clean box has a disadvantage in that dust-containing air stays in the vicinity of the clean box and prevents contamination of the wafer.
[0008]
[Means for Solving the Problems]
The present application is a mini-environment unit for processing a wafer, and is attached to the mini-environment unit, takes air from outside the mini-environment unit, pressurizes the interior to a higher pressure than the outside, and air from above to below A fan that generates the main flow of the wafer, a clean box in which the wafer is stored, a wafer loading / unloading port for loading / unloading the wafer between the clean box and the mini-environment unit, and a wafer loading / unloading A wafer processing apparatus including a door that closes the wafer loading / unloading port when not performed and opens the wafer loading / unloading port when loading / unloading the wafer, even when the door closes the wafer loading / unloading port A first gap remains in communication between the mini-environment part and the outside, and the first gap Provides a wafer processing apparatus, wherein the upstream side of the gap of the main flow of the air is greater than the gap between the downstream. By making the downstream gap of the air flow generated by the fan larger than the upstream gap, the downstream flow rate is not made slower than the upstream side, and the differential pressure inside and outside at both points is made as uniform as possible. It is. Thereby, the disturbance in the downstream gap portion can be reduced, and the dust-proof function can be prevented from being lowered even in the gap portion away from the fan.
The present application further includes a mini-environment unit that receives a wafer from a clean box in which the wafer is stored and pressurizes the interior to a pressure higher than the outside to process the wafer, and a load port that holds the clean box A wafer processing apparatus comprising a table, wherein the mini-environment unit takes in and out a wafer inlet / outlet for loading / unloading a wafer, and pressurizes the interior to a higher pressure than the outside by taking in air from the outside of the mini-environment unit And a fan for generating a main flow of air from top to bottom, the clean box has an opening for taking out the wafer and a lid for closing the opening, and the load port table is a wafer Can be transferred between the mini-environment part and the clean box. The clean box can be placed at an interval so that the opening and the wafer loading / unloading opening face each other and the opening of the clean box is not in contact with the mini-environment portion, and the wafer loading / unloading is placed on the load port table. Provided is a wafer processing apparatus comprising a second gap extending along the wafer loading / unloading port in the vicinity of the mouth. By disposing the second gap in the load port table, the load port table is prevented from obstructing the air flow, and air flow stagnation is prevented under the clean box to prevent wafer contamination.
[0009]
【Example】
(Example 1)
Hereinafter, Example 1 will be described with reference to the drawings. FIG. 1 is an overall view of the wafer processing apparatus 10. The wafer processing apparatus 10 includes a mini-environment unit 5 and a load port table 15. A clean box 6 is used to move the wafer 7 between the wafer processing apparatuses 10. The wafer 7 is housed in a clean box 6 and closed with a highly airtight lid 4. A high cleanliness is guaranteed inside the clean box 6 in which the wafer 7 is accommodated. For example, the inside is filled with high purity nitrogen or the like.
[0010]
A robot arm 11 for moving the wafer 7 is attached inside the mini-environment unit 5. A fan (not shown) is attached to the upper portion of the mini-environment unit 5 to send air outside the mini-environment to the inside. As a result, the pressure is higher than the external pressure (usually atmospheric pressure) of the wafer processing apparatus 10. Further, the fan generates a so-called down-flow air flow from the upper side to the lower side of the mini-environment part.
On the wall surface of the mini-environment unit 5, a wafer loading / unloading port 2 through which the robot arm 11 receives the wafer 7 from the clean box 6 is arranged. A door 3 for closing the wafer loading / unloading port 2 is disposed inside the mini-environment unit 5 and corresponding to the wafer loading / unloading port 2. A holding mechanism 21 is disposed on the surface of the door 3. The holding mechanism 21 is, for example, a vacuum suction port, and holds the lid 4 of the clean box 7 so as to be attracted to the surface by performing suction from this port. The door 3 rotates around a fulcrum 22 prepared in the drive unit 20 for raising and lowering, and moves toward or away from the wafer loading / unloading port 2. Accordingly, the door 3 closes the wafer loading / unloading port 2 when the wafer 7 is not transferred, and the door 3 holds the lid 4 of the clean box 7 by the holding mechanism 21 when the wafer 7 is transferred. As shown in FIG. 1, the wafer loading / unloading port 2 is opened by rotating around the fulcrum 22. The door 3 can be moved up and down (up and down in FIG. 1) by the drive unit 20. After the door 3 has completely opened the wafer loading / unloading port 2 as shown by the dotted line in FIG. 1, the door 3 descends from it and is retracted. On the other hand, when the door 3 closes the wafer loading / unloading port 2, the door 3 moves in a process opposite to the above. That is, after the drive unit 20 is raised from the retracted position to the fixed position, the drive unit 20 is rotated about the fulcrum 22 to close the wafer loading / unloading port 2 and the lid 4 is inserted into the clean box 6.
[0011]
On the load port table 15, a docking plate 12 for holding and placing the clean box 6 is provided. The docking plate 12 is movable along a rail located under the docking plate 12 in a direction approaching or moving away from the wafer loading / unloading port (left-right direction in FIG. 1). When the clean box 6 is placed on the docking plate 12 and is brought close to the mini-environment unit 5, the vertical direction (vertical direction of the wafer loading / unloading port 2) and the horizontal position are such that the lid 4 just faces the wafer loading / unloading port 2. The position in the direction (lateral direction of the wafer loading / unloading port 2) is adjusted. At this time, the clean box 6 approached by the docking plate 12 does not come into contact with the mini-environment part 5 and the clean box 7 is placed at an interval so that the opening of the clean box 6 does not come into contact with the mini-environment part. The stop position of the docking plate 12 in the wafer loading / unloading direction is adjusted so as to be possible. The interval is about 2 mm, for example.
[0012]
Next, with reference to FIG. 2, a state where the door 3 closes the wafer loading / unloading port 2 will be described. FIG. 2 is a view of the mini-environment portion 5 viewed from the clean box 7 side in a state where the door 3 closes the wafer loading / unloading port 2. On the wall surface of the mini-environment portion 5, a wafer loading / unloading port 2, which is a substantially rectangular shape and communicates with the inside and outside of the mini-environment portion, is disposed. The door 3 is adjusted so as to be disposed at a substantially central portion of the wafer loading / unloading port 2. The size of the door 3 is slightly smaller than the size of the wafer loading / unloading port 2, and even when the door 3 closes the wafer loading / unloading port 2, the first gap 1 that communicates the inside and the outside of the mini-environment part. Is formed between the door 3 and the wafer loading / unloading port 2. It should be noted that the size of the first gap 1 in FIG. 2 is exaggerated due to the visual problem of the first gap 1.
The first gap 1 has a large size above the mini-environment portion and a small size below the mini-environment portion. This is because the main flow of air is generated as a down flow from the upper side to the lower side due to the fan being arranged on the inner upper part of the mini-environment part 5, so that the downstream side of the main flow of air in the first gap 1. This gap is made larger than the upstream gap . The difference in size of the first gap 1 is preferably set so that the air flow flowing out from the first gap 1 does not cause a difference between the upper side and the lower side.
[0013]
Next, how the apparatus of this embodiment operates will be described.
First, a state where the wafer 7 is not delivered will be described. In this state, the wafer loading / unloading port 2 is closed by the door 3 as shown in FIGS. At this time, air steadily flows out from the inside of the mini-environment part 5 set to a pressure higher than the outside through the first gap 1 to the outside. Therefore, the internal and external differential pressure generated by pressurization is small in the vicinity of the door 3. Furthermore, from the first gap 1 since then larger than the upstream side of the gap the gap between the downstream of the main flow of air, the speed and the lower side 1b of the air flow flowing out of the first gap 1 of the upper 1a The velocity of the flowing air flow is almost equal. Therefore, the differential pressure in the vicinity of the first gap 1 can be made substantially equal regardless of the upstream side and the downstream side of the main flow of air.
Next, a state where the wafer 7 is delivered from the clean box 6 will be described. In this state, the clean box 6 is carried from the other processing apparatus and placed on the docking plate 12 after the previous processing process in the other processing apparatus is completed. The mounted clean box 6 moves along with the movement of the docking plate 12 until the lid 4 comes close to the door 3 of the mini-environment unit 5 through the wafer loading / unloading port 2. After the docking plate 12 stops, the door 3 holds the lid 4 by vacuum suction by the holding mechanism 21 and opens the wafer loading / unloading port 2 together with the lid 4. As described above, when the wafer loading / unloading port 2 is blocked by the door 3, the pressure difference between the inside and outside of the mini-environment portion 5 is already small, so that the resistance due to the pressure difference is small and the door 3 can be easily opened. Can do. Further, the disturbed air flow generated from the inside of the mini-environment portion 5 to the outside when the door 3 is opened is also reduced. Therefore, the disturbed air flow containing dust is not drawn into the clean box 6, and the disturbed air flow further agitates the dust existing around the wafer inlet / outlet 2 to result in the clean box 6. Entrainment can be prevented. In particular, since the differential pressure in the vicinity of the first gap 1 is almost equal regardless of the upstream and downstream sides of the main flow of air, the upstream side around the door 3 even when the door 3 is opened. Regardless of the downstream side, there is no difference in the turbulent flow of air generated by opening the door 3. Therefore, it is possible to prevent the problem of deterioration of the function of contaminating the wafer 7 due to the turbulent air flow on the lower side of the door 3.
Thereafter, the door 3 is lowered by the driving unit 20 while holding the lid 4, and the wafer 7 is carried into the mini-environment unit 5 by the robot arm 11. After the wafer 7 is stored at a predetermined position inside the mini-environment unit 5, the door 3 is raised again by the driving unit 20 to close the wafer loading / unloading port 2 and the delivery of the wafer 7 is completed.
[0014]
(Example 2)
A second embodiment in which the second gap 8 is arranged in the load port table 15 will be described with reference to FIG. FIG. 3 is an enlarged view of the load port table 15 when the door 3 opens the wafer loading / unloading port 2. A docking plate 12 is disposed on the load port table 15, and the docking plate 12 is movable so as to approach or leave the wafer loading / unloading port 2. In order to facilitate understanding, the clean box 6 is omitted in FIG. 3, but in this state, the clean box 6 is in a state where the opening of the clean box 6 with the lid 4 opened is opposed to the wafer loading / unloading port 2. Is placed on the docking plate 12. That is, the load port table 15 has the clean box opening and the wafer loading / unloading opening facing each other so that the wafer 7 can be transferred between the mini-environment unit 5 and the clean box 6, and the opening of the clean box 6 is the mini-opening. Clean boxes are placed at intervals that do not contact the environment. The load port table 15 is provided with a long and narrow second gap 8 extending along the wafer loading / unloading port 2 in the vicinity of the wafer loading / unloading port 2.
[0015]
Next, how the second embodiment works will be described.
When the door 3 closes the wafer loading / unloading port 2, air flows from the first gap 1, while when the door 3 opens the wafer loading / unloading port 2, the air flows out from the wafer loading / unloading port 2 itself toward the outside of the mini-environment part. ing. Since the clean box 6 and the mini-environment unit 5 are not in contact with each other, the clean box 6 flows out from the wafer loading / unloading port 2 to the load port table 15 side. Since the docking plate 12 and the clean box 6 are placed on the load port table 15, a substantial flow cross-sectional area cannot be secured, and this air flow is obstructed. Since this air contains dust, if the air flow is blocked and stagnation occurs in this vicinity, the air flow containing dust flows into the clean box 6 and leads to contamination of the wafer 6. However, since the load port table 15 is provided with a long and narrow second gap 8 extending along the wafer loading / unloading port 2 in the vicinity of the wafer loading / unloading port 2, a flow area is secured, and the air flow including dust is It is possible to prevent the wafer 7 from being discharged from the second gap 8 to the outside.
[0016]
In Examples 1 and 2, it is preferable to select the most appropriate width for the first gap 1 and the second gap 8 in relation to the pressure inside the mini-environment. In addition, it is necessary to select the most appropriate one in relation to the pressure inside the mini-environment as to how much the size of the downstream gap in the first gap is larger than that of the upstream gap.
Furthermore, in the first embodiment, the size of the wafer loading / unloading port 2 is rectangular and the size of the door 3 is small on the lower side. However, the door 3 is rectangular and the shape of the wafer loading / unloading port 2 is used to form the first gap 1. Setting the size has the same effect.
Furthermore, as shown in FIG. 2, the width on the side surface side of the door 3 extending in the air flow direction in the first gap 1 is adjusted to reduce the upstream width of the main air flow. On the other hand, the same effect can be obtained by increasing the width on the downstream side.
[0017]
【The invention's effect】
The following effects can be realized by the present invention.
(1) By making the downstream gap of the air flow generated by the fan larger than the upstream gap, the disturbance in the vicinity of the downstream gap is reduced, and the dust-proof function is lowered even in the gap away from the fan. be able to.
(2) By arranging the gap in the load port table, the load port table and other articles are prevented from obstructing the air flow, and the stagnation of the air flow below the clean box is prevented.
[0018]
[Brief description of the drawings]
FIG. 1 is an overall view of a semiconductor wafer processing apparatus to which the present invention is applied.
FIG. 2 is a view showing the vicinity of a wafer loading / unloading port of the semiconductor wafer processing apparatus according to the first embodiment.
FIG. 3 is a view showing the vicinity of a load port table in the second embodiment.
[Explanation of symbols]
1,8 Clearance 2 Wafer loading / unloading entrance 3 Door (Mini environment part)
4 Lid 5 Mini environment unit 6 Clean box 7 Wafer 10 Semiconductor wafer processing device 11 Robot arm 12 Docking plate 15 Load port table

Claims (2)

A mini-environment unit for processing wafers;
A fan that is attached to the mini-environment part, takes air from the outside of the mini-environment part, pressurizes the inside to a pressure higher than the outside, and generates a main flow of air from above to below and a wafer inside A clean box where
A wafer loading / unloading port for loading / unloading a wafer between the clean box and the mini-environment unit;
A wafer processing apparatus comprising a door that closes the wafer loading / unloading port when the wafer is not loaded / unloaded and opens the wafer loading / unloading port when loading / unloading the wafer,
Even when the door closes the wafer loading / unloading port, a first gap remains between the mini-environment portion and the outside,
The wafer processing apparatus, wherein the first gap has a larger gap on the downstream side of the main flow of air than an upstream gap . A wafer comprising a mini-environment unit that receives a wafer from a clean box in which the wafer is stored and pressurizes the interior to a higher pressure than the outside to process the wafer, and a load port table that holds the clean box A processing device comprising:
The mini-environment part has a wafer inlet / outlet for taking in and out of the wafer, and takes air from the outside of the mini-environment part to pressurize the interior to a higher pressure than the outside and main flow of air from above to below And a fan that produces
The clean box has an opening for taking out the wafer and a lid for closing the opening,
The load port table has the opening and the wafer loading / unloading opening facing each other so that a wafer can be transferred between the mini-environment part and the clean box, and the opening of the clean box is located in the mini-environment part. Clean boxes can be placed at intervals that do not touch,
The wafer processing apparatus, wherein the load port table has a second gap extending along the wafer loading / unloading port in the vicinity of the wafer loading / unloading port.

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