JP2001060574A - Semiconductor wafer cleaning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a semiconductor wafer cleaning system to clean and dry semiconductor wafers, while isolating the wafers from the atmosphere by improving the cleaning effect of the device by bringing plates closer to the surfaces of a wafer to be cleaned, while a fluid is jetted from ejectors. SOLUTION: When wafers 5 to be cleaned are taken out one by one from a wafer supplying section 10A, by means of a wafer transfer means 6 and the presence of one wafer 5 is confirmed from the light made incident to a light receiver 19b from a light emitter 19a, pure water is jetted from a fluid ejector 11a through a fluid supplying port A and an upper plate 1 and is brought closer to the wafer 5 by means of a plate moving means 3 until the wafer 5 is sucked to the internal surface of the plate 1 by Bernoulli effect. Thereafter, the wafer 5 is accurately positioned and brought closer to a lower plate 2, until the distance between the wafer 5 and plate 2 becomes a preset value together with the upper plate 1, while the pure water is jetted from a fluid ejector 12a through another fluid supplying port B and the wafer 5 is held in a state that the wafer 5 is sucked from both the top and bottom sides. Under this condition, the upper and lower surfaces of the wafer 5 are simultaneously cleaned by jetting a liquid chemical upon the surfaces from the ejectors 11a and 12a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning apparatus used for cleaning a semiconductor wafer with a chemical solution in a process of manufacturing a semiconductor device or the like.

[0002]

2. Description of the Related Art In a cleaning process in semiconductor manufacturing, high-temperature mixed cleaning of sulfuric acid and hydrogen peroxide ((SPM)), high-temperature mixed cleaning of ammonia and hydrogen peroxide (SC1), and high-temperature mixed cleaning of hydrochloric acid and hydrogen peroxide are mainly used. Cleaning (SC2) and natural oxide film removal cleaning (DHF) using dilute hydrofluoric acid are used in combination depending on the type of contamination to be removed, and an etching process includes etching of a silicon oxide film (BHF) using buffered hydrofluoric acid. ), Silicon nitride film etching with hot phosphoric acid, and wafer etching with a mixed solution of hydrofluoric acid and nitric acid are widely used, and in these chemical cleaning steps or etching steps, cleaning with pure water is performed each time each step is completed. After all the cleaning or etching steps are completed, a drying process such as spin drying is performed as a final process.

Conventionally, such cleaning and the like are performed by a multi-tank type cleaning apparatus. However, the number of tanks is increased, the apparatus is increased in size, a large amount of chemical solution and pure water are required, and wafers between the tanks are required. Contamination such as particles occurs during transfer. There were problems such as the inability to block oxygen and the like in the air. As a means for solving these problems, a single-wafer cleaning apparatus for cleaning wafers one by one has been developed.However, in the conventional single-wafer cleaning apparatus, a chemical solution or pure water supplied to the wafer is subjected to surface tension. As a result, a sufficient cleaning effect cannot be obtained due to rolling on the wafer surface. If the wafer surface is hydrophilic and covered with a silicon oxide film, etc., it can be spread evenly on the wafer surface by supplying a large amount of chemical solution or pure water and rotating the wafer at high speed. When the surface is exposed, even with such a method, the wafer surface cannot be uniformly covered with the chemical solution or pure water. Furthermore, in single-wafer cleaning, it is structurally difficult to perform rinsing with pure water while shutting it off from the atmosphere. Since the rinsing is performed in a state exposed to the atmosphere, oxygen in the atmosphere dissolves in the pure water and dissolved oxygen is dissolved. Thus, formation of a natural oxide film could not be prevented.

[0004]

In a general single-wafer cleaning apparatus, cleaning is performed by discharging a chemical solution, pure water, etc. from a nozzle on a wafer onto a wafer surface. As a method for improving the cleaning effect, And JP-B-8-28342. In this method, the liquid is caused to flow from an umbrella-shaped cover disposed on the wafer, and the cleaning effect is improved by utilizing the negative pressure generated by the liquid flowing out at high speed from the periphery of the wafer and the cover, that is, the Bernoulli effect. Things. However, in this method, the cleaning effect on the back surface of the wafer cannot be performed due to the inability to clean the back surface of the wafer and the umbrella shape. It was not possible to sufficiently clean a fine and deep pattern having a high aspect ratio.

SUMMARY OF THE INVENTION An object of the present invention is to solve the various problems existing in the above-mentioned conventional single-wafer cleaning apparatus, and to clean and dry the wafer with excellent cleaning effect while shielding the wafer from the atmosphere. Another object of the present invention is to provide a small-sized semiconductor wafer cleaning apparatus capable of transporting a processed wafer while being shielded from the atmosphere and transporting the processed wafer to a preliminary chamber shielded from the atmosphere.

[0006]

In order to achieve the above object, a semiconductor wafer cleaning apparatus according to the present invention is provided with a fluid flow path for supplying a liquid and a gas, and a fluid ejection port located at the tip of the fluid flow path. A flat plate, and proximity means for bringing the surface of the flat plate provided with the fluid ejection port and the wafer close to each other.

In the above apparatus configuration, for example, the wafer to be cleaned placed in the wafer placement space is placed in a state where the flat plate ejects any one of a cleaning chemical solution, pure water, and a drying gas for drying the wafer from the fluid ejection port. By approaching the surface, the wafer is sucked and floated on the flat plate using the Bernoulli effect generated by the fluid flowing at high speed between the flat plate and the wafer surface, forming a narrow gap without contact between the flat plate and the wafer. The wafer surface can be uniformly covered with high-speed cleaning chemicals, pure water, gas, etc., regardless of the hydrophilicity or hydrophobicity of the wafer surface.
The steps of etching, pure water rinsing, and drying can be performed without exposing to the atmosphere, and all the problems of the wafer cleaning step in the conventional IC manufacturing can be solved.

In the apparatus according to the present invention, the flat plate does not need to be a flat plate as a whole, but the point is that the surface forming the fluid ejection port is flat. In addition, as the proximity means for bringing the surface of the flat plate with the fluid ejection port and the wafer close to each other, any means that can bring the surface of the flat plate with the fluid ejection port and the wafer close to each other in a substantially horizontal state. It is sufficient that various known moving mechanisms can be applied. That is, as a specific embodiment, first, in the case where it is constituted by wafer transfer means such as vacuum tweezers for taking a wafer in and out of a wafer arrangement space opposed to a flat plate, the second embodiment
In the case of using a plate moving means for bringing a flat plate closer to a wafer arranged in a wafer arrangement space, thirdly, a combination of the wafer transferring means and the plate transferring means is adopted. Further, the apparatus of the present invention is carried into a wafer arrangement space of the apparatus by wafer transfer means such as vacuum tweezers, and a flat plate is approached from above to a substantially horizontally arranged wafer to clean the upper surface of the wafer. It is also possible to adopt a form in which a flat plate is also provided on the lower side, and this is brought close to the lower surface of the wafer similarly to the upper flat plate, so that both surfaces of the wafer are simultaneously cleaned. In the former,
Instead of the plate moving means for bringing the flat plate close to the wafer, a structure in which a mechanism for moving the wafer in the vertical direction is added to the wafer transferring means can be adopted. In the latter, as the plate moving means for bringing the flat plate close to the wafer, a configuration provided on one of the upper flat plate and the lower flat plate, a configuration provided on both the upper and lower flat plates may be used, but at least the upper flat plate is provided. Is preferred. Further, when a wafer is loaded into the wafer placement space by means of wafer transfer means such as vacuum tweezers, the plate movement means is unnecessary if the flat plate is set at a predetermined position suitable for holding the wafer by using the Bernoulli effect. However, only the wafer transfer means may be used as the proximity means.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating a main part of the apparatus according to the embodiment of the present invention. This semiconductor wafer cleaning apparatus includes upper and lower flat plates 1 and 2, a plate moving means 3 for moving the upper flat plate 1, and a wafer for transferring a wafer 5 into and out of a wafer placement space 4 set between the upper and lower flat plates 1 and 2. Transfer means 6 and 7, width shifting means 8 for moving wafer 5 arranged in wafer placement space 4, fluid supply means 9, wafer supply unit 10 A for stocking wafer 5 to be cleaned and wafer 5 after cleaning And a spare room 10B for receiving the

The upper and lower flat plates 1 and 2 have fluid passages 11 and 12 provided at the center and penetrating vertically.
The two fluid ejection ports 11 a and 12 a are installed so as to face each other across the wafer arrangement space 4. In this example, the lower flat plate 2 is fixedly arranged, and the upper flat plate 1 is vertically moved by the plate moving means 3. The plate moving means 3 is constituted by a cylinder driving unit 13, and connects the cylindrical portion forming the fluid flow path 11 of the upper plate 1 to the tip of an arm 13a connected to a cylinder rod, thereby drawing the upper plate 1. 1 moves in the Y arrow direction. FIG. 1 shows a state in which the upper flat plate 1 is maximally raised. In addition, the fluid injection ports 11a, 11a,
12a is opened only at the center of each of the flat plates 1 and 2 as shown in FIG. 2 (a), but is not limited to this, and FIG.
As shown in FIG. 1, the auxiliary fluid ejection port 19a may be provided together with the fluid ejection port 11a or 12a. The auxiliary fluid injection port 19a is located at the tip of an auxiliary fluid passage flow provided in an inclined state (not shown) corresponding to the fluid flow paths 11 and 12. The auxiliary fluid passage fluid and the auxiliary fluid ejection ports 19a are provided at equal intervals on the circumference around the ejection port 11a or 12a, and are inclined in the circumferential tangential direction from the direction perpendicular to the flat plate. The fluid can be ejected at different angles.

The wafer transfer means 6 and 7 are formed of vacuum tweezers capable of holding the wafer 5 by a suction method, and are connected to a hand portion of a robot (not shown) to control the movement.
The wafer transfer means 6 holds the wafers 5 in the wafer supply unit 10A one by one and transfers them to the wafer placement space 4. The wafer transfer means 7 holds the washed wafer 5 in the wafer placement space 4 and transfers it to the preliminary chamber 10B. In addition, a strain gauge 14 is provided at an outer end of the vacuum pin cent as the wafer transfer means 6. The wafer supply unit 10A holds a number of wafers 5 to be cleaned at a known cassette type wafer loading position. The preliminary chamber 10B is filled with an inert gas, and is configured to be able to receive the cleaned wafer 5 in a state of being shielded from the atmosphere. On the other hand, the width shifter 8 includes a guide plate 16 provided in a state where the position is regulated on the upper surface side of the upper flat plate 1, and a pair of width shift pins 16 a moved along the guide plate 16. The wafers 5 in the wafer placement space 4 are centered from both sides by moving the both width shift pins 16a in the direction of the arrow X in FIG. As described above, as the basic members of the apparatus, the fluid flow paths 11 and 12 for supplying the liquid and the gas and the fluid ejection ports 11 a and 1 located at the tips of the fluid flow paths 11 and 12 are provided.
Flat plates 11 and 12 provided at the center of the plate, wafer transfer means 6 and 7 for transferring wafers 5 into and out of the wafer placement space 4 facing the flat plates 11 and 12, and wafer placement space 4
Plate moving means 3 for moving the flat plates 11 and 12 to bring the surfaces having the fluid ejection ports 11a and 12a closer to the wafer 5 disposed at the same position. Since the part can be designed in accordance with mass productivity, the form of the wafer 5, and the like, it is versatile.

Ultrasonic means 17 and cooling means 18 are assembled on the lower plate 2 on the outer surface side opposite to the fluid ejection port 12a. Among them, the ultrasonic means 17 is known for ultrasonic cleaning, and can apply ultrasonic waves toward the inner surface of the lower flat plate 2 located on the same side as the fluid ejection port 12a. The cooling means 18 is provided as needed, and has a configuration in which cooling water is introduced from an inlet 18a on one end and discharged from an outlet 18b on the other end. Reference numeral 19a denotes a light emitting device.
From a, a light beam is emitted toward the wafer 5 in the wafer arrangement space 4. Reference numeral 19b denotes a light receiver, which detects the presence of the wafer 5 by receiving light reflected on the wafer 5.

Hereinafter, an operation example of the semiconductor wafer cleaning apparatus having the above configuration will be described in detail. Here, the fluid supply means 9 includes a chemical liquid supply unit 20, a pure water supply unit 21, and an inert gas supply unit 22 such as nitrogen gas. However, the present invention is not limited to this. For example, the chemical liquid supply unit may be omitted. Conversely, a configuration may be adopted in which the chemical solution supply unit can selectively supply different types of chemical solutions.
The fluid supply means 9 is capable of pumping a chemical solution, pure water, and gas from each of the supply parts 20, 21, 22 at a predetermined flow rate through a dedicated flow control valve or the like, and has a switching means 23. ing. The switching means 23 selectively supplies the fluid supply ports A and B of the fluid flow paths 11 and 12 in the upper and lower flat plates 1 and 2 via the pipes 24 and 25 to selectively supply any of the chemical, pure water and gas.
Can be selectively supplied to

First, the wafers 5 to be cleaned are taken out one by one from the wafer supply unit 10A by vacuum tweezers as the wafer transfer means 7. Then, when the taken out wafer 5 is located in the wafer arrangement space 4 and is stopped almost at the center of the upper and lower flat plates 1 and 2, a signal is sent to the control device (not shown), and the light emitting device 19a sends the signal to the wafer. Light is irradiated toward the wafer 5, and the presence of the wafer 5 is confirmed by the light receiver 19b.

As described above, when the control device confirms the presence of the wafer 5 based on the light incident signal on the light receiver 19b,
Pure water is supplied to the fluid supply port A and is ejected from the fluid ejection port 11a. Next, when the upper plate 1 is brought closer to the wafer 5 by the plate moving means 3, the wafer 5 is moved to the inner side of the upper plate 1 by the Bernoulli effect. Is adsorbed. After the control device confirms the generation of the suction force of the Bernoulli effect through the strain gauge 14, when the suction of the wafer 5 by the wafer transfer means 7 is stopped, the wafer 5 is lifted up while maintaining a narrow gap where pure water flows. It is held on the flat plate 1. Here, the wafer 5 is accurately held at the center of the upper flat plate 1 by moving the width shifting pins 16a that are opened on both sides of the wafer 5 toward the fluid ejection port 11a. From this state, the wafer 5 is brought closer to the lower plate 2 with the upper plate 1 through the plate moving means 3 to a predetermined distance in a state where pure water is supplied to the fluid supply port B and is ejected from the fluid ejection port 12a. Then, the wafer 5 is held in a state of being sucked from the upper plate 1 and the lower plate 2 respectively.
In this state, when the chemical is supplied to the fluid supply ports A and B and is ejected from the fluid ejection ports 11a and 12a, the upper surface and the lower surface of the wafer 5 are simultaneously cleaned.

When the cleaning is completed, the chemical is switched to pure water again. If wafer cleaning with another type of chemical is required, pure water is switched to that chemical, and the cleaning process proceeds according to the procedure described above.
In this way, cleaning with all necessary chemicals is completed,
When the final rinse with pure water is completed, fluid supply port A
And B are supplied with the dried gas (nitrogen gas) and are ejected from the fluid ejection ports 11a and 12a. Then, since the pure water attached to the wafer 5 can be blown off in a short time, the wafer can be efficiently dried by the same effect as blowing off pure water by centrifugal force by the conventional spin rotation.

It is important that when the supply fluids are switched at the same time, if the supply to the fluid supplies A and B is switched at the same time, both flow rates instantaneously become zero and the wafer 5 can be held. Disappears. For this reason, as a control point, for example, the fluid supply port B is switched and then the fluid supply port A is switched so that the wafer 5 is always held on either the upper plate 1 or the lower plate 2 side. It is.

Then, the wafer 5 after cleaning and drying is completed.
Are stored in the wafer cassette of the preliminary chamber 10B by the wafer transfer means 7. Thus, in the device of the present invention,
Since cleaning with a chemical solution at a high flow rate and rinsing with pure water are possible, it is effective in removing contamination adhering to the wafer 5, and the cleaning chemical solution with pure water can be efficiently and quickly washed away. In addition, cleaning and rinsing can be performed in an environment shielded from the surrounding atmosphere. For example, if pure water having a small amount of dissolved oxygen is used in advance for pure water rinsing after removing a natural oxide film with dilute hydrofluoric acid, natural Generation of an oxide film can be prevented. In addition, chemical solution cleaning and pure water rinsing can be performed in a state where the ultrasonic means 17 is driven and ultrasonic waves are applied to the wafer 5 as necessary, so that an effective cleaning that has never been achieved before is realized. Further, when pulsation is given when supplying the supplied cleaning chemical solution, pure water, and gas for drying the wafer, the suction force for suctioning the wafer 5 to the upper and lower flat plates 1 and 2 also changes, so that more effective cleaning can be performed. it can. The apparatus of the present invention is shown in FIG.
When the fluid is ejected from the auxiliary fluid ejection port 19a together with the fluid ejection port 11a or 12a as shown in (b), more rapid and uniform cleaning can be realized, and the cleaning action is reduced even if the wafer 5 has a large diameter. Can be eliminated.

The basic configuration of the apparatus according to the present invention has been described above, but the detailed configuration can be further developed based on the apparatus capability, the form of the target wafer, and the like. As a development example, for example, as schematically shown in FIG. 3, a transfer mechanism for transferring the upper flat plate 1 (a mechanism that can transfer vertically and horizontally) may be provided.
Is transferred to the preparatory chamber 10B together with the wafer 5, so that the wafer 5 after the cleaning is transferred to the preparatory chamber 10B to be shielded from the atmosphere. That is, the preliminary chamber 10B is installed adjacent to the cleaning chamber 10 in which the apparatus of the present invention is installed, and is formed in a space state in which the inside is shielded from the outside air.
It has a gate 30 provided on the upper side. Then, after the cleaning and drying processing, the wafer 5 is transferred together with the upper flat plate 1 to a position directly above the gate 30 in a state where the nitrogen gas is continuously injected and the wafer 5 is adsorbed. Then, the wafer is held by a wafer holding and transferring mechanism (not shown) provided on the side of the preliminary chamber 10B, and at the same time, the holding of the upper flat plate 1 on the wafer 5 is released, and the gate 30 is closed. The vacuum chamber 10C provided adjacent to the preparatory chamber 10B is a heat treatment apparatus for performing the following processing on the washed wafer 5,
This is where the CVD equipment and the like are installed. This vacuum chamber 10C
Is communicated with the spare room 10B via the opening / closing gate 31,
The wafer 5 can be transferred from the preliminary chamber 10B side to the vacuum chamber 10C side through the gate 31 in a state of being completely shielded from the atmosphere. In this way, it becomes easy to connect the cleaning apparatus of the present invention to the heat treatment apparatus, the CVD apparatus, and the like in the vacuum chamber 10C through the preliminary chamber 10B in a state of being cut off from the atmosphere. Integration is achieved.

[0020]

As described above, according to the apparatus of the present invention, a high-speed fluid flows from the center of the wafer toward the periphery thereof, and a suction force is generated by the Bernoulli effect over the entire surface of the wafer, and a sufficient cleaning effect is exhibited. The cleaning of the pattern having the aspect ratio is sufficiently achieved, and the same effect as the high-speed spin drying is achieved in the drying treatment. Further, in the apparatus of the present invention, cleaning,
Since there is no mechanical contact for holding the wafer during drying,
The cleaning and drying of the wafer are sufficiently performed, and there is no risk of the wafer being damaged due to mechanical contact. The cleaning, drying, and subsequent wafer transfer in the apparatus of the present invention can be easily performed in a state in which the wafer is shielded from the atmosphere. When the upper and lower flat plates are provided, it is possible to simultaneously clean both surfaces of the wafer.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a semiconductor wafer cleaning apparatus to which the present invention is applied.

FIG. 2 is a view showing a flat plate fluid ejection port of the above-described apparatus and a modified example thereof.

FIG. 3 is a schematic diagram showing an example of a configuration in which the above-described apparatus is connected to an apparatus in the next step.

[Explanation of symbols]

 1 and 2 are upper and lower flat plates 3 is a plate moving means 4 is a wafer placement space 5 is a wafer 6, 7 is a wafer transfer means 8 is a width shifting means 9 is a fluid supply means 10A is a wafer supply unit 10B is a preliminary chamber 11, 12 is The fluid flow paths 11a and 12a are fluid ejection ports 19a are auxiliary fluid ejection ports 20 are chemical liquid supply sections 21 are pure water supply sections 22 are gas supply sections 23 are switching means

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hironori Shioya 215-1 Oiso-cho, Naka-gun, Kanagawa F term (reference) 3B116 AA03 AB13 AB23 AB42 BB24 BB32 BB85 CD33 3B201 AA03 AB13 AB23 AB42 BB24 BB32 BB85 BB93 BB95 BB96 BB98 CD33

Claims (6)

[Claims] 1. A flat plate provided with a fluid flow path for supplying a liquid and a gas, and a fluid ejection port located at a tip of the fluid flow path, and a surface of the flat plate provided with the fluid ejection port is in close proximity to a wafer. A semiconductor wafer cleaning apparatus, comprising: 2. The semiconductor wafer cleaning apparatus according to claim 1, wherein said flat plate is provided vertically. 3. The semiconductor wafer cleaning apparatus according to claim 1, further comprising a fluid supply unit and a switching unit that switchably supply a chemical solution, pure water, and a gas to the fluid flow path. 4. The semiconductor wafer cleaning apparatus according to claim 1, further comprising an ultrasonic unit for applying an ultrasonic wave to said flat plate. 5. A plurality of auxiliary fluid ejection ports for ejecting a fluid at an angle inclined from a vertical direction to a circumferential tangential direction on a circumference of the flat plate around a fluid ejection port. 4
The semiconductor wafer cleaning apparatus according to any one of the above. 6. The semiconductor according to claim 1, further comprising a transfer mechanism for transferring the flat plate, and a spare chamber for receiving a wafer in a space in which outside air is blocked from the flat plate transferred by the transfer mechanism. Wafer cleaning equipment.