JPH10308376A - Cleaning of wafer and wafer cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make easy to remove dusts from the surface of each wafer and also to eliminate the readhesion of the dusts and to shorten the cleaning time for the wafers by a method wherein a plurality of the wafers are stacked vertically in a horizontal state leaving a gap between the wafers in the interior of a cassette, which is housed in a cleaning tank, and a cleaning liquid is allowed to horizontally flow in layers among the wafers. SOLUTION: A cassette 12 with a plurality of wafers W lap-arranged vertically in a horizontal state therein is set at a prescribed position in a cleaning tank 11 in such a way that the direction of an opening formed in the cassette is aligned with the direction of the flow of a cleaning liquid. When a circulating pump 20 is actuated, the cleaning liquid in the tank 11 is sucked in a cleaning liquid circulating path 18 via each suction nozzle 17 in the vicinities of other side plates 11b. Foreign substances in the sucked cleaning liquid are removed by a filter 19. The cleaning liquid in the interior of the tank 11 is horizontally flowed in the gaps among the wafers W in the cassette 12 in the state of a laminar flow and dusts or the like adhered to the wafers W are removed and are eliminated to the outside through narrow depth side ports 12b formed in the cassette 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer cleaning apparatus and a method for cleaning the same, and more particularly, to a reduction in cleaning time and an improvement in wafer cleaning performance.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer cleaning apparatus and a cleaning method thereof, in which the stability of a wafer in a cassette during cleaning and accompanying cassette handling is good.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 4 and 5, for example, there are known wafer cleaning apparatuses provided in a wet type cleaning line for silicon wafers. FIG. 4 is a schematic vertical sectional view of a wafer cleaning apparatus according to a conventional means,
FIG. 5 is a schematic vertical sectional view of a wafer cleaning apparatus according to another conventional means. That is, the conventional cleaning apparatus 10 shown in FIG.
0, the cassette 102 accommodating a plurality of wafers W in the cleaning tank 101 is inserted into the wafer loading / unloading port 10.
2a is stored upward, and the cleaning liquid is injected while bubbling from the bottom of the cleaning tank 101, thereby causing the cleaning liquid to flow vertically into the gaps between the wafers W to remove dust (particles and the like) on the wafer surface. Remove. Note that the wafers W are arranged vertically in the tank length direction with a gap therebetween. The overflow liquid containing the cassette 102 is collected at the upper part of the cleaning tank 101, and is thereafter circulated and used by a pump.

[0003] Another conventional cleaning device 20 shown in FIG.
0, a cassette 202 in which a number of wafers W are vertically stored with a gap therebetween is set inside the cleaning tank 201, and a cleaning solution is flown from the side of the cleaning tank 201, and the wafer W in the cassette 202 is set. Is to wash. That is, the cleaning liquid flowing from one side surface of the cleaning tank 201 toward the cassette 202 is supplied to the wafer loading / unloading port 20 facing upward.
2a, flows downward from one side edge into the cassette 202,
Thereafter, each wafer W is washed while generating a turbulent flow inside the cassette 202, and flows out from the other side of the wafer inlet / outlet 202a of the cassette 202 to the opposite side of the cleaning tank 201. Note that the cleaning liquid is also taken in and out from the narrow rear side opening 202b of the cassette 202. 4 and 5, reference numeral 103 denotes a filter for the cleaning liquid after cleaning, and reference numeral 104 denotes a circulation pump.

[0004]

However, these prior arts have the following disadvantages. That is, in the case of the conventional cleaning apparatus 100, the cleaning liquid is caused to flow upward from the bottom of the tank by arranging the wafers W in a vertical state.
There is a risk that the dust will be caught in the turbulence generated at the top of the wafer W, and that the dust will adhere to the wafer W again, or unwashed residue will occur. In addition, a relatively long cleaning time was required.

Further, in the case of another conventional cleaning apparatus 200, when the flow of the cleaning liquid in the cleaning tank 201 is specifically examined, as described above, the cleaning liquid is supplied to the cassette 202 from the wafer inlet / outlet 202a disposed upward. After flowing into the inside 202, the wafer W is cleaned and discharged to the outside while generating turbulent flow inside the inside, so that the flow has a relatively low flow rate. Therefore, the cleaning takes a long time, the cleaning performance of each wafer W is poor, and the cleaning is left with a large number of unwashed portions.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention can reduce the cleaning time, improve the cleaning performance of the wafer, and improve the stability of the wafer in the cassette during cleaning and the accompanying handling of the cassette. Providing a simple wafer cleaning method and its cleaning apparatus,
That is the purpose. It is another object of the present invention to provide a wafer cleaning apparatus and a cleaning method capable of reusing a cleaning liquid after cleaning. It is another object of the present invention to provide a wafer cleaning apparatus capable of easily producing a horizontal laminar flow of a cleaning liquid in a cleaning tank. It is still another object of the present invention to provide a wafer cleaning apparatus capable of producing a smooth horizontal laminar flow in a cleaning tank and smoothly discharging floating dust to the outside.

[0007]

According to the first aspect of the present invention, a plurality of wafers are spaced from each other in a cassette housed in a cleaning tank and having an opening aligned with a flow direction of a cleaning liquid. This is a wafer cleaning method in which cleaning is performed by stacking vertically on a horizontal state and laminating a cleaning liquid horizontally between the wafers. The washing tank here means, for example, RCA
APM (ammonia / hydrogen peroxide solution) tank for cleaning,
Various washing tanks, such as a washing tank (rinse tank) and an HF tank, may be mentioned. Along with this, the cleaning liquid used in the cleaning tank includes:
For example, various cleaning liquids such as APM, pure water, and HF can be used.

According to a second aspect of the present invention, there is provided the wafer cleaning method according to the first aspect, wherein the cleaning liquid after the cleaning is circulated.

According to a third aspect of the present invention, there is provided a cleaning tank, a cassette provided so as to be able to be taken in and out of the cleaning tank, and accommodating a plurality of wafers with a gap therebetween, provided in the cleaning tank. In a wafer cleaning apparatus comprising: a cleaning means for flowing a cleaning liquid into a gap between wafers inserted in the cassette, the cassette is a storage body for vertically stacking the wafers inserted in a horizontal state. Yes,
Further, the cleaning means flows the cleaning liquid from one side of the cleaning tank toward the opposite side thereof, so that the cleaning liquid is horizontally spread between the wafers housed in the cassette whose opening direction is aligned with the flow direction of the cleaning liquid. This is a wafer cleaning device that performs laminar flow.

[0010] The cleaning means referred to here is of any type as long as it has a horizontal laminar flow when passing between wafers, and can flow a cleaning solution from one side of the cleaning tank to the opposite side. May be. For example, even if the cleaning liquid is pumped into the cleaning tank from one side of the cleaning tank, the cleaning liquid flows into the cleaning tank by sucking the cleaning liquid inside the cleaning tank from the opposite side of the cleaning tank. However, both may be used in combination. In addition, when used together, it is preferable that the amount of the cleaning liquid pumped into the cleaning tank per hour and the amount of suction per hour of sucking the cleaning liquid out of the tank be substantially equal because a stable laminar flow can be generated.

The invention according to claim 4 is the wafer cleaning apparatus according to claim 3, wherein the cleaning means is of a cleaning liquid circulation type. As the cleaning liquid circulation type cleaning means, for example, there is a cleaning liquid in which a circulation pump, a cleaning liquid filter, and the like are connected in the middle of the cleaning liquid circulation path. Further, when the cleaning liquid is a chemical, a concentration sensor and a concentration adjusting means for adding a chemical solution to the circulation path from a chemical solution tank based on a concentration detection signal from the sensor may be provided as necessary. Good.

According to a fifth aspect of the present invention, the surface on the opposite side of the cleaning tank is divided into a plurality of areas, and each of the areas is provided with a cleaning liquid tapered gradually toward the back in the flow direction of the cleaning liquid. 5. The wafer cleaning apparatus according to claim 3, wherein a suction nozzle is provided, and each of the suction nozzles is connected to a cleaning liquid suction unit. This area may be of any size and shape. For example, a square having a side of 5 cm arranged in a lattice shape may be used. If the lattice shape is used, a laminar flow with a more uniform flow velocity can appear in the cleaning tank, and the cleaning performance of each wafer can be further improved.

According to a sixth aspect of the present invention, an opening / closing lid is provided at an upper portion of the cleaning tank, and a discharge port for floating debris is formed at an upper portion on an opposite side of the cleaning tank. A wafer cleaning apparatus according to any one of the above. The opening / closing lid here may be any type of opening / closing lid, such as a hinged rotation type and a horizontal slide type. Further, the outlet may be formed by cutting out one end of the opening / closing lid,
It may be simply a gap between the upper edge of the cleaning tank and the opening / closing lid.

[0014]

According to the wafer cleaning apparatus and the cleaning method of the present invention, when the cleaning liquid flows from the opening direction of the cassette accommodated in the cleaning tank with the opening direction aligned with the flow direction of the cleaning liquid, the cleaning liquid is supplied to the cassette. The wafer flows substantially horizontally in a laminar flow state through the gaps between the wafers stacked vertically in a horizontal state. With such a horizontal laminar flow, the turbulence of the cleaning liquid in the cassette hardly occurs, and the laminar flow of the cleaning liquid is smoothly performed. Therefore, dust removed from the surface of each wafer is hardly reattached, and furthermore, there is little unwashed residue, and the wafer can be washed well. As a result, the cleaning time can be reduced.

Further, since each wafer is stored in the cassette in a horizontal state, the state is easily stabilized by its own weight.
Therefore, for example, even if the flow rate of the cleaning liquid is relatively increased during cleaning, fluttering of each wafer is unlikely to occur, which can prevent damage to the wafer surface during cleaning, and may cause wafers to fall off the cassette during cleaning. Also decreases. Moreover, since the wafers are horizontally inserted into the cassette in this way, the state is stabilized by their own weight,
For example, even when a cassette is taken in and out of the liquid level in the cleaning tank using a robot hand, there is little risk that stored wafers fall off or the wafer surface is damaged by vibration.

In particular, according to the second and fourth aspects of the present invention, the cleaning liquid after cleaning is collected, and is again flown into the cleaning tank to be circulated and used as the cleaning liquid for the wafer. Depending on the type of cleaning liquid and the type of cleaning liquid, the cost for detoxification can be reduced.

In the invention according to claim 5, when the cleaning liquid reaches the vicinity of the surface on the opposite side of the cleaning tank, the negative pressure of the suction means causes each area formed separately on the surface on the opposite side to be formed. Since it is sucked from the so-called trumpet-shaped suction nozzle gradually tapered to the back side in the flow direction of the cleaning liquid, a laminar flow with a relatively uniform flow velocity can appear in the cleaning tank, and the The cleaning performance can be improved.

Further, in the invention according to the sixth aspect, since the opening / closing lid is provided on the upper portion of the cleaning tank, the cleaning liquid flowing in the cleaning tank in the horizontal direction overflows even if the flow rate is larger than the tank capacity. And a good horizontal laminar flow can be obtained. In addition, since the floating dust floating near the liquid surface during the flow is discharged from the discharge port as it is, the floating dust can be treated irrespective of the provision of the opening / closing lid.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. Here, wafer cleaning in which the wafer is rinsed with ultrapure water will be described as an example.
FIG. 1 is a schematic longitudinal sectional view of a wafer cleaning apparatus according to one embodiment of the present invention, and FIG. 2 is an enlarged front view of a suction nozzle formed by area division on a surface on the opposite side of a cleaning tank.
FIG. 3 is an enlarged perspective view of the cassette stored in the cleaning tank.

In FIG. 1, reference numeral 10 denotes a wafer cleaning apparatus. The wafer cleaning apparatus 10 is provided with a horizontally long cleaning tank 11 for storing a cleaning liquid which is ultrapure water, and is provided so as to be capable of being taken in and out of the cleaning tank 11. A cassette 12 for accommodating a plurality of wafers W with a gap therebetween and a cleaning liquid circulation type cleaning means 13 provided in the cleaning tank 11 for flowing a cleaning liquid through the gap between the wafers W inserted in the cassette 12 And At the top of the cleaning tank 11, a horizontal slide-type opening / closing lid 11c capable of closing from one end to the vicinity of the other end is provided. The length of the opening / closing lid 11c is slightly shorter than the entire length of the opening of the cleaning tank 11. As a result, an outlet 15 for the floating dust 14 is formed between the other end of the opening and the tip of the opening / closing lid 11c. The other end of the opening of the cleaning tank 11 is slightly warped.

On one side plate 11a of the cleaning tank 11, a cleaning liquid inflow hole 111a is formed at a predetermined pitch. Also,
A water jacket 16 for temporarily storing the cleaning liquid is attached to the outer surface of the one side plate 11a. The other side plate 11b of the cleaning tank 11 is divided into a plurality of areas in which squares each having a side of 5 cm are arranged in a grid. In each area, a suction nozzle 17 for the cleaning liquid, which is gradually tapered toward the back in the flow direction of the cleaning liquid, is formed (see also FIG. 2).
Each suction nozzle 17 disposed downstream of the cleaning tank 11;
Water jacket 1 arranged upstream of cleaning tank 11
6 is connected via a cleaning liquid circulation path 18 of the cleaning means 13.

The cleaning means 13 has a filter 19 and a circulation pump 20 which are sequentially connected in the middle of the cleaning liquid circulation path 18 and also serve as suction means. An on-off valve 21 is connected to the cleaning liquid circulation path 18 in the vicinity of each suction nozzle 17. When the circulation pump 20 is operated, the cleaning liquid in the cleaning tank 11 is sucked from each suction nozzle 17 to the cleaning liquid circulation path 18. The washing liquid is filtered by a filter 19 on the way, flows into the water jacket 16 and is supplied to the one side plate 11.
a through the inlet 111a formed in the cleaning tank 1 again.
Flow into 1. The washing liquid continuously repeats this circulation. As shown in FIG. 3, the cassette 12 is provided with a wafer loading / unloading port 12a for loading / unloading the horizontally arranged wafers W.
Is formed on one side surface (front side surface), and the other side portion facing this surface is gradually tapered to form a vertically long rear side opening 12b.

Next, a wafer cleaning method according to an embodiment of the present invention using the wafer cleaning apparatus 10 will be described. As shown in FIG. 1, the open / close lid 11c is opened, and a cassette 12 in which a plurality of wafers W are stacked vertically in a horizontal state is placed in a cleaning tank 11 in which a cleaning liquid is stored. Is set at the predetermined position, and the opening / closing lid 11c is closed again. At this time, the cassette 12
The opening direction is aligned with the flow direction of the cleaning liquid. That is, the cassette loading / unloading port 12a is connected to one side plate 1 of the cleaning tank 11.
The cleaning tank 11 is set at the center of the cleaning tank 11 in the direction of 1a and with the rear opening 12b facing the other side plate 11c.

After that, when each of the on-off valves 21 is opened and the circulation pump 20 is operated, the cleaning liquid in the cleaning tank 11 is sucked into the cleaning liquid circulation path 18 through each suction nozzle 17 near the other side plate 11b. The suctioned cleaning liquid passes through the filter 19 to remove foreign substances and the like, and then the cleaning tank 1
1 is temporarily stored in a water jacket 16 provided on the upstream side. The washing liquid filtered in the water jacket 16 is supplied to a plurality of inlets 11 formed in one side plate 11a.
It flows into the cleaning tank 11 via 1a.

The flowing washing liquid also receives the suction action from each suction nozzle 17 and flows in the washing tank 11 in the direction of the arrows in FIGS. Inside the cleaning tank 11, the wafer W
Is set in such a manner that the directions of the openings 12a and 12b are aligned with the flow direction of the cleaning liquid. That is, the cleaning liquid flowing toward the other side plate 11b side is
The cleaning liquid flows into the cassette 12 from the wafer loading / unloading port 12a of the cassette 12, and thereafter, the cleaning liquid flows horizontally in a laminar flow state in the gap between the wafers W stacked one above the other in the horizontal state. At this time, dust and the like adhering to the wafer W are removed, and the narrow rear side opening 1 of the cassette 12 is removed.
2b is discharged outside.

As described above, since the flow of the cleaning liquid in the cassette 12 becomes a horizontal laminar flow as it passes through the gap between the wafers W, the cleaning liquid flows upward from the bottom of the cleaning tank shown in FIG. 4, for example. Compared with a conventional cleaning apparatus for cleaning a vertically placed wafer by flowing and a cleaning apparatus in which a cleaning liquid flows from a side of a cleaning tank to a cassette having a wafer inlet and outlet shown in FIG. And the turbulence of the cleaning liquid near the liquid surface does not easily occur, and the laminar flow of the cleaning liquid is smoothed. This makes it difficult for the dust and the like removed from the surface of each wafer W to adhere again, and it is possible to wash well with little unwashed residue. As a result, the cleaning time is reduced.

Further, since each wafer W stored in the cassette 21 is stored in the cassette 12 in a horizontal state, the state is easily stabilized by its own weight. Thus, for example, even if the flow rate of the cleaning liquid is relatively increased during cleaning, each wafer W
Is less likely to flutter due to the cleaning fluid having a high flow rate, and damage to the surface of the wafer W during cleaning due to this can be prevented. In addition, the possibility that the wafer W falls off from the cassette 12 during cleaning is reduced. In addition, since the state of the wafer W thus horizontally inserted into the cassette 12 is stabilized by its own weight, the wafer W is transmitted from the robot hand side even when the cassette 12 is put in and out of the cleaning tank 11 by the robot hand. The risk of the wafer 12 falling off due to vibration or the like is small.

The cleaning liquid discharged from the rear side opening 12b of the cassette 12 is sucked through the respective suction nozzles 17 by the operation of the circulation pump 20 on the other side plate 11b side of the cleaning tank 11, and the filter 19 , And is circulated and used as a cleaning solution for the wafer W. As a result, resources can be reused, cleaning costs can be reduced, and costs for detoxification processing can be reduced depending on the type of cleaning liquid. When the cleaning liquid reaches the vicinity of the surface on the opposite side of the cleaning tank 11 as described above, the wrapper-shaped suction nozzle 17 of each area formed separately on the surface on the opposite side is caused by the negative pressure of the circulation pump 20. Through the cleaning liquid circulation path 18, the laminar flow having a relatively uniform flow velocity is applied to the cleaning tank 1.
Can be made within one. Thereby, the cleaning performance of each wafer W can be improved. Since each area has a lattice shape of 5 cm, a laminar flow having a more uniform flow velocity can be generated in the cleaning tank 11, and the cleaning performance of each wafer W can be further improved. In addition, on the upstream side of the cleaning liquid 11, a large number of cleaning liquid inlets 111a are formed in the one side plate 11a at a predetermined pitch, so that a laminar flow with a uniform flow velocity can be more easily produced.

Further, an opening / closing lid 11c is provided above the cleaning tank 11.
Is provided, the cleaning liquid flowing in the cleaning tank 11 in the horizontal direction does not overflow even if the flow rate is large with respect to the tank capacity, and a good horizontal laminar flow can appear. In addition, since the floating dust 14 near the liquid surface is discharged as it is from the discharge port 15 on the downstream side of the cleaning tank 11, the floating dust 14 can be treated irrespective of the provision of the opening / closing lid 11c. that's all,
Although the embodiment has been described, the present invention is not limited to this embodiment, and even if there is a design change without departing from the gist, the present invention is included in the present invention. For example, in the embodiment, the suction means for sucking the cleaning liquid in the cleaning tank from the suction nozzle is also used as the circulation pump of the cleaning liquid circulation means. However, the present invention is not limited to this, and may be separate.

[0030]

According to the wafer cleaning apparatus and the cleaning method thereof according to the present invention, the wafers are vertically stacked in the cassette in a horizontal state, and the flow of the cleaning liquid in the cassette is made into a horizontal laminar flow. The laminar flow between the wafers becomes smooth, dust is easily removed from the surface of each wafer, and the removed dust and the like are less likely to be reattached. As a result, the cleaning time can be reduced. Further, since each wafer is horizontally inserted into the cassette in this manner, the state of the wafer is easily stabilized in the cassette by its own weight, and therefore, even if the flow rate of the cleaning liquid is increased, the wafer is less likely to flutter. Thus, the surface of the wafer during cleaning is less likely to be damaged in the cassette, and the risk of wafers falling off the cassette during cleaning or accompanying cassette handling is reduced.

In particular, in the inventions according to the second and fourth aspects, the cleaning liquid after cleaning is circulated and used, so that resources are reused, the cleaning cost is reduced, and the detoxification treatment is performed depending on the type of cleaning liquid. Cost can be reduced.

According to the fifth aspect of the present invention, when the cleaning liquid in the cleaning tank is circulated, the cleaning liquid after cleaning is sucked into the circulation system using the suction nozzles divided into a plurality of areas. Thus, a laminar flow having a relatively uniform flow velocity can be produced, and the cleaning performance of each wafer can be improved.

Further, in the invention according to the sixth aspect, since the opening / closing lid is provided on the upper part of the cleaning tank, even if the flow rate of the cleaning liquid in the cleaning tank increases, a good horizontal laminar flow can be obtained without overflow. I can get out. In addition, since the floating dust near the liquid surface during the flow is discharged from the discharge port, the floating waste can be treated despite the provision of the opening / closing lid.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of a wafer cleaning apparatus according to one embodiment of the present invention.

FIG. 2 is an enlarged front view of a suction nozzle formed on an opposite surface of a cleaning tank by area division.

FIG. 3 is an enlarged perspective view of a cassette stored in a cleaning tank.

FIG. 4 is a schematic vertical sectional view of a wafer cleaning apparatus according to a conventional means.

FIG. 5 is a schematic longitudinal sectional view of a wafer cleaning apparatus according to another conventional means.

[Explanation of symbols]

 Reference Signs List 10 wafer cleaning device, 11 cleaning tank, 11c opening / closing lid, 12 cassette, 13 cleaning means, 14 floating dust, 15 discharge port, 17 suction nozzle, 20 circulation pump (suction means), W wafer.

Claims (6)

[Claims] 1. A plurality of wafers are vertically stacked with a gap therebetween in a cassette housed in a cleaning tank and having an opening aligned with a flow direction of a cleaning liquid,
A method of cleaning a wafer in which a cleaning liquid is horizontally laminarly flowed between these wafers for cleaning. 2. The wafer cleaning method according to claim 1, wherein the cleaning liquid after the cleaning is circulated. 3. A cleaning tank, a cassette provided to be able to be taken in and out of the cleaning tank, and accommodating a plurality of wafers with a gap therebetween, provided in the cleaning tank, and inserted into the cassette. A cleaning means for flowing a cleaning liquid into a gap between each of the wafers, wherein the cassette is a container for vertically stacking the wafers inserted in a horizontal state, and the cleaning means Wafer cleaning in which the cleaning liquid is caused to flow from one side of the cleaning tank toward the opposite side thereof, so that the cleaning liquid flows horizontally between the wafers housed in the cassette whose opening direction is aligned with the flow direction of the cleaning liquid. apparatus. 4. The wafer cleaning apparatus according to claim 3, wherein said cleaning means is of a cleaning liquid circulation type. 5. A surface of the cleaning tank on the opposite side is divided into a plurality of areas, and in each of these areas, a suction nozzle for the cleaning liquid that is gradually tapered toward the back in the flow direction of the cleaning liquid is provided. 5. The wafer cleaning apparatus according to claim 3, wherein each of the suction nozzles is connected to a cleaning liquid suction unit. 6. The cleaning tank according to claim 3, wherein an opening / closing lid is provided at an upper portion of the washing tank, and a discharge port for floating debris is formed at an upper portion on an opposite side of the washing tank. 3. The wafer cleaning apparatus according to claim 1.