JP2002093764A - Cleaning equipment of wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clean wafers more efficiently while dealing with sudden occurrence of abnormality by solving the problems of a prior art QCR bath. SOLUTION: In the cleaning equipment of wafer being used in semiconductor production process, a rinse bath 1 comprises punching side boards 7a and 7b disposed between the opposite sidewalls 3a and 3b while spaced apart from each other. A pair of liquid introducing sections 10a and 10b extending vertically through the bath are formed between the sidewalls 3a and 3b corresponding to the punching side boards 7a and 7b. Cleaning liquid is introduced to the liquid introducing sections 10a and 10b from lower supply ports 4a and 4b and introduced through the holes of the punching side boards 7a and 7b into a bath cleaning section 1A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer cleaning apparatus suitable for a cleaning step of cleaning a wafer with a chemical solution or pure water in a semiconductor manufacturing process. In this specification, “chemical liquid and pure water” are collectively referred to as a cleaning liquid unless it is necessary to distinguish them.

[0002]

2. Description of the Related Art Cleaning processes in semiconductor manufacturing include cleaning using a high-temperature mixture of sulfuric acid and hydrogen peroxide for the purpose of removing organic contaminants, and a high-temperature mixture of hydrochloric acid and hydrogen peroxide for the purpose of removing heavy metal contamination. There is cleaning using a high-temperature mixed solution of ammonia and hydrogen peroxide for the purpose of cleaning and removing particulate contamination. In actual wafer production, these cleanings are used alone or in combination depending on the contamination status of the wafer and the wafer process. As the etching process, a silicon oxide film etching using buffered hydrofluoric acid and a silicon nitride film etching using hot phosphoric acid are widely used. In wafer cleaning with these chemicals (including etching), when wafer processing with chemicals is completed, the cleaning process is performed successively with pure water, and then cleaning with another chemical is performed. As described above, a combination of the treatment with the chemical solution and the subsequent treatment with pure water constitutes a unit process of wafer cleaning. In actual wafer cleaning, several such unit processes are combined.

[0003] In the semiconductor manufacturing process, since the wafer cleaning is repeatedly performed so as to say "begins with the cleaning and ends with the cleaning", a large amount of pure water is consumed.
According to one theory, a 200 mm wafer requires 6 tons of pure water per wafer, and the 300 mm wafer that will be in full swing will consume more pure water, and a measure to save pure water is required. . In recent years, it has been required to reduce energy consumption in order to reduce the emission of carbon dioxide, which is a substance causing global warming. However, it is said that about 20 kWh of electricity is required for each ton of pure water produced. Therefore, reduction of pure water consumption is also strongly demanded from the viewpoint of prevention of global warming.

As described above, in order to satisfy the demand for reducing pure water consumption, the rinsing efficiency in a rinsing tank that consumes most of pure water in semiconductor production is increased to enable the effective use of pure water. A rinsing tank capable of dramatically reducing the consumption of pure water, that is, an apparatus structure for introducing a pure water from above one side of the tank to form a downward water flow and an overflow water flow has been invented (Japanese Patent No. 20131691). According to the present invention, rapid replacement that can save 40% or more of pure water can be achieved as compared with a so-called overflow rinse (hereinafter referred to as OFR) tank in which pure water is introduced from the lower part of the tank and overflows from the upper part, which has been widely used. Rinse (hereinafter referred to as QCR)
The tank was developed (Miyakoshi, et al., "QC Cleaning-New Wafer Cleaning by Rapid Replacement Method in Rinse Rinse", Proceedings of the 16th Air Cleaning and Contamination Control Research Conference p.216, (1999), Miyagoshi, Others, QC Cleaning-New Wafer Cleaning by Rapid Replacement Method in Cleaning Rinse Tank (3), Proceedings of the 18th Air Purification and Contamination Control Research Conference, p.95, (2000).

[0005]

The above-mentioned QCR tank is:
By reducing the generation of vortex water flow generated in the rinsing tank, the supplied pure water and the solution in the tank are stirred and not mixed,
Since the solution in the tank can be rapidly replaced with the supplied pure water, the chemicals attached to the wafer and the wafer cassette transferred to the rinse tank after the chemical processing are mixed with pure water previously in the rinse tank. The action of diluting is also weakened, and rinsing is started with a thick chemical attached,
Rinsing efficiency was poor. Fortunately, the improvement in the rinsing efficiency of the QCR tank is so high that it is much more efficient than the OFR tank, even if the problem of high-concentration chemical solution adhesion at the start of rinsing is subtracted. It just didn't matter. Such a low effect of thinning the adhering chemical solution at the start of rinsing weakens the quenching effect of the rinsing of the oxide film etching by dilute hydrofluoric acid or the like, and thus has a problem of etching variation. In addition, in the conventional QCR tank, pure water is supplied only from one side. In a mass-production wafer cleaning apparatus for simultaneously cleaning four cassettes in two rows and two rows in total, the pure water supply side and the opposite side are used. Thus, there was a difference in the rinsing effect, the rinsing time was prolonged, and the reduction of the pure water / water saving effect was a problem. In addition, Q draining from the bottom of the tank
In the CR tank, the water level of the rinsing tank drops until the wafer is exposed from the water surface due to sudden power failure, stoppage of pure water supply, malfunction of the water gauge, etc., and the solution adhering to the exposed wafer surface evaporates. As a result, the evaporation residue becomes fine particles, causing particle contamination and causing irreparable damage to the wafer.

The present invention solves the above-mentioned problems of the conventional QCR tank, and enables efficient wafer cleaning with a small amount of pure water or chemical solution, excellent etching and rinsing uniformity, and sudden occurrence of abnormalities. It is an object of the present invention to provide a highly reliable wafer cleaning apparatus which does not cause recoverable damage to a wafer. Another object of the present invention is to improve the economical efficiency by utilizing pure water having a low degree of contamination, which is finally used in a case where washing is performed plural times, in another rinsing tank.

[0007]

According to the present invention, the following arrangement is devised to achieve the above object. Claim 1
The present invention is used in a semiconductor manufacturing process as exemplified in FIG. 2 and the like, and in a wafer cleaning apparatus for cleaning by placing a wafer c in a rinsing tank 1 having a drain port 2 at the bottom of the tank, the rinsing tank 1 Punching side plates 7a, 7b provided with a gap between the side walls 3a, 3b to be formed, and the side walls 3 corresponding to the punching side plates 7a, 7b.
a, 3b, liquid introduction parts 10a, 10 extending vertically
b is formed as a pair, and the cleaning liquid is
10b is supplied from the lower supply ports 4a and 4b, and is introduced into the tank cleaning unit 1A from the holes of the punching side plates 7a and 7b. In this structure, the liquid introducing portions 10a, 10b extending on the both sides of the tank are formed by the punching side plates 7a, 7b, so that the cleaning liquid is alternately supplied to the tank cleaning portion 1A from the holes of the punching side plates 7a, 7b. It becomes possible. Further, the cleaning liquid is supplied to the tank cleaning section 1A from a plurality of holes of the punching side plates 7a and 7b on both sides.
Since the horizontal water flow is introduced into the tank cleaning section 1A exclusively from the holes at the uppermost stages of the a and 7b, the overflow water surface water flow can be formed.

The invention according to claim 7 is used in a semiconductor manufacturing process as exemplified in FIG.
In the wafer cleaning apparatus for cleaning the wafer, the rinsing tank 1 is provided with supply ports 4a and 4b through which cleaning liquid is supplied into the tank via valves 30a and 30b, and valves 31 and 3 for supplying cleaning liquid in the tank.
A discharge port 2 for discharging through the tank 2, 33, etc., means 15a, 15b or 16a, 16b capable of detecting the level of the cleaning liquid in the tank and transmitting it as a water level (or water level) signal 26; 30a, 30b, 31, 32, 33
Control device 27A for controlling the opening and closing of the water surface signal 2
6 and a monitoring device 27B that opens and closes the valves 30a, 30b and the like independently of the control device 27A. In this structure, by providing the monitoring device 27B independent of the control device 27A, it is possible to prevent the wafer c from being exposed from the water surface even when an abnormality occurs at the time of detecting the water surface as in the embodiment.

A ninth aspect of the present invention is a wafer cleaning apparatus used in a semiconductor manufacturing process as illustrated in FIGS. 2 and 3 for cleaning a wafer c by placing it in a rinsing tank 1. Rotation driving means 1 for rotating a plurality of wafers c in a cassette 20 placed in a tank in a state where
7 is characterized. In this structure,
In the process of cleaning with a chemical solution or pure water, variations in the degree of cleaning and etching that tend to occur in the upper and lower portions of the wafer c are eliminated, and uniform cleaning and etching can be reliably achieved. This is because the improvement effect becomes more remarkable as the diameter of the wafer c increases.
Also, if the wafer c is not rotated as in the prior art, the wafer c
Of the outer peripheral portion of the vertical groove 20a may be insufficiently cleaned or etched. This structure can solve such a problem at the same time.

The invention according to claim 11 is a wafer cleaning apparatus used in a semiconductor manufacturing process as illustrated in FIG. 4, wherein a wafer c is sequentially placed in at least a first rinsing tank 40 A and a second rinsing tank 40 B for cleaning. The first rinsing tank 4
The first rinsing tank 40A and the second rinsing tank 40B are configured to supply pure water from a supply port 41 provided at a bottom of the tank and to discharge the pure water in the tank by overflowing from the top of the tank. Are arranged side by side so as to be lower than the second rinsing bath 40B, and the second rinsing bath 40
A discharge port 43 of a water collecting section 42 for accommodating pure water overflowing from B and a supply port 41 of the first rinsing tank 40A are connected by a pipe, and overflow to the water collecting section 42 of the second rinsing tank 40B. Purified water is supplied to both rinsing tanks 40
A, the first rinsing tank 4 depends on the water level difference due to the step of 40B.
It is characterized by being introduced into 0A.
In this structure, for example, when the second rinsing tank 40B is used in the final cleaning step, pure water with little dirt used there is used again for cleaning in the previous step. The overflowed pure water in the rinsing tank 40B is supplied to the first rinsing tank 40 according to the water level difference between the two tanks 40A and 40B.
It is significant that the automatic transfer into the container A does not require a liquid transfer power such as a pump and the accompanying equipment, and realizes a continuous transfer.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 4 schematically shows the entire semiconductor wafer cleaning equipment to which the present invention is applied, and FIG.
FIG. 4 is a schematic configuration diagram mainly showing a drive system of a rinsing tank used at an early stage in the cleaning equipment of FIG. FIG. 2A is a schematic configuration diagram of the rinsing tank of FIG. 1 as viewed from above, and FIG.
FIG. 4 is a cross-sectional view taken along a line A. 3 (a) and 3 (b) are schematic views showing the operation of the rotary drive means of the rinsing bath, taken along the line BB in FIG. 2 (a).

The cleaning equipment shown in FIG. 4 is used when the wafer c having been subjected to chemical cleaning is rinsed with pure water in the rinsing tank 1 and then pure water with the other first rinsing tank 40A and second rinsing tank 40B. It is a structural example. Here, the rinsing tank 1 and the first
The second rinsing tanks 40A and 40B themselves constitute the wafer cleaning apparatus of the present invention. Although the wafer cleaning apparatus mainly including the rinsing tank 1 is premised on pure water cleaning, it is also possible to perform chemical liquid cleaning using this. In contrast, the first and second
The rinsing tanks 40A and 40B are for performing pure water cleaning exclusively. However, in principle, a chemical solution may be used.
And, in relation to the present invention, the wafer cleaning apparatus according to claims 1 to 10 has a configuration related to the rinsing tank 1,
The wafer cleaning apparatus according to claim 11 specifies a configuration related to the first and second rinsing tanks 40A and 40B.

(Wafer Cleaning Apparatus Using Rinse Tank 1) This wafer cleaning apparatus includes a mass-production type rinse tank 1 for simultaneously cleaning a total of four wafer cassettes 20 in two rows as shown in FIGS. Mainly, the tank structure and its control mechanism are devised. Next, the main device structural features will be described in detail.

(Tank structure) The rinsing tank 1 has a liquid inlet 10 between a discharge port 2 and a side wall 3a, 3b provided at the bottom of the tank.
Punching side plates 7a, 7 defining partitions 10a, 10b
b, the overflow drainage part 5 in which the upper end of the side wall 3b is lowered, the punching lower plate 8 arranged on the lower side in the tank, and the pipe 13 arranged in the gap between the punching lower plate 8 and the tank bottom.
Gas injection means comprising two water gauges 15a, 15
b, a rotary drive means 19 for rotating and vertically swinging the wafers c arranged and accommodated in the cassette 20.

The form of the rinsing tank 1 is shown in FIG. 2 as a substantially rectangular container having an upper opening which is defined by side walls 3a, 3b and side walls 3c, 3d whose sides are opposed to each other and whose lower side is defined by a gentle V-shaped bottom wall 3e. No. The side wall 3b is set slightly lower than the side wall 3a, and the upper end forms the overflow drain section 5. A water collecting part 6 is provided outside the side wall 3b.
The water collecting part 6 is a place where the cleaning liquid overflowing from the overflow drain part 5 is received and drained. The bottom wall 3e is provided with a discharge port 2 at the center, and supply ports 4a and 4b are provided at appropriate positions close to the side walls 3a and 3b. Punching side plates 7a, 7b and punching lower plate 8
Has a plurality of holes provided up, down, left, and right for passing a cleaning liquid. The punching side plates 7a, 7b are provided with side walls 3c, 3d.
The liquid introducing portions 10a and 10b are formed so as to be detachably held by a holding member 9 fixed on the inner surface of the opposite side and fixed in the vertical direction and extending vertically with the corresponding side walls 3a and 3b. The hole distribution of the punching side plates 7a and 7b is appropriately devised, for example, by increasing the number of holes on the upper side or increasing the hole diameter on the upper side than the hole diameter on the lower side. The liquid introduction sections 10a and 10b communicate with the corresponding supply ports 4a and 4b. On the other hand, the punching lower plate 8 is
e, and is provided on the corresponding convex portion of e to form a predetermined gap with the bottom wall 3e. On the punching lower plate 8, four frame-shaped receiving bases 11 and six bearing members 12 are provided. The receiving table 11 has a frame shape for positioning and holding the cassettes 20. The bearing member 12 pivotally supports a rotation rod 19 of a rotation drive mechanism 17 described later. Therefore, the inside of the rinsing tank 1 is formed by the side walls 3c and 3d.
, The punching side plates 7a and 7b, and the punching lower plate 8 form a tank cleaning unit 1A. The cleaning liquid is supplied to the tank cleaning section 1A from the supply ports 4a, 4b through the liquid introduction sections 10a, 1a.
0b, respectively, from which the punching side plates 7a,
7b through a plurality of holes. In this liquid supply mode, the cleaning liquid is smoothly supplied as a flat water flow through the holes of the punching side plates 7a and 7b on both sides having a height corresponding to the amount of water in the tank. The cleaning liquid in the tank is
And when the tank washing section 1A is full, it can also be discharged from the overflow drain section 5 on the upper side. In this liquid discharging mode, the presence of the punching lower plate 8 eliminates local deviation of the liquid part discharged from the discharging part 2, and also removes foreign substances floating on the water surface in the tank due to the presence of the overflow draining part 5, A clean water surface free of foreign matter can be formed. The punching side plates 7a, 7b
Can be integrally formed with the rinsing tank 1, but if it is detachably assembled via the holding member 9, it is excellent in maintainability and versatility.

(Gas injection means and water level gauge)
A small hole is opened along the upper longitudinal direction, and nitrogen gas or the like is injected into the tank cleaning unit 1A through the punching lower plate 8. The pipe 13 is bent in correspondence with the left and right cradles 11, and is provided on the inner surface side of the bottom wall 3 e.
4. When both ends of the pipe 13 are led out of the tank and connected to a gas supply pipe 22 described later, the pipe 13 operates as a gas injection unit. Water level gauge 15a, 1
5b is installed at an appropriate position in the tank by a post-installation method. The water level gauge 15a is a high water level gauge, and detects a state immediately before the washing liquid is filled in the tank and overflows from the overflow drain section 5. The water level gauge 15b is a low water level water level gauge, and detects a state when the cleaning liquid is in the tank and fills the cassette 20. The detection value of each water level gauge 15a, 15b is
Of the water surface signals 26a, 2b which are sent via signal lines to the external processing units 16a, 16b installed outside the
6b is transmitted to the contact signal interface 25.

(Rotation Driving Means) The rotation driving means 17 is provided in a state where the cassette 20 is positioned and held on the pedestal 11.
The plurality of wafers c in the cassette 20 are simultaneously rotated and vertically swung. In this example, it is composed of a rotating power section 18 installed outside the side wall 3d and a rotating rod 19 pivotally supported by the bearing member 12 described above. The rotation power unit 18 is composed of a motor or the like. The rotating rod 19 has a cylindrical member 19b having an elliptical cross section around the axis of a perfect circular shaft 19a.
Is attached. The cylindrical member 19b is made of an elastic rubber material and is integrally mounted except for both side portions of the shaft 19a. The shaft 19a is connected at its base end to the rotary power unit 18, and is rotated integrally with the cylindrical member 19b by the driving of the rotary power unit 18. The cassette 20 has a plurality of opposed vertical grooves 20a as in the conventional case.
This is a structure in which a large number of wafers c are regularly housed vertically in 0a.

The above-mentioned rotary driving means 1
7, when the cassette 20 is held by the receiving table 11, the wafer c in the cassette 20 is supported on the elliptical cylindrical member 19 b of the rotating rod 19. In this setting state, when the rotating rod 19 is rotated by the rotation driving means 17, the wafer c is moved into the vertical groove 20a as shown in FIGS.
While being rotated in the state of being inside, it is swung up and down along the vertical groove 20a according to the degree of elliptical deformation. This advantage is that, in the process of cleaning with a chemical solution or pure water, variations in the degree of cleaning and etching that are likely to occur in the upper and lower portions of the wafer c can be eliminated, and uniform cleaning and etching can be improved. Become. If the wafer c is not rotated as in the prior art, the vertical groove 2 is formed in the outer peripheral portion of the wafer c.
Although cleaning or insufficient etching of the portion located within 0a occurs, such a problem can be solved.

(Rinse tank 1)
As shown in FIG. 1, a liquid supply pipe 21 for sending pure water or a chemical solution is connected to each of the supply ports 4a and 4b, a gas supply pipe 22 for sending a target gas is connected to both ends of the gas injection pipe 13, The liquid discharge pipe 23 is connected to the outlet 2. Among them, the liquid supply pipe 21 has a tube 21a having both ends connected to the supply ports 4a and 4b, and a tube 21b connecting the liquid supply source and the tube 21a.
Consists of Both sides of the pipe 21a, that is, the supply ports 4a, 4b
Automatic valve (a valve that performs only opening and closing operations) 30a,
30b is attached. Supply port 4 of pipe 21a
On the a side, a bypass valve 21c is provided with an automatic valve 30a interposed therebetween, and a needle valve (flow regulating valve) is provided in the bypass pipe 21c.
30c and an automatic valve (a valve that performs only an opening / closing operation) 30d are provided. A liquid pressure gauge 35 and a liquid flow meter 36 are attached to the pipe portion 21b. Flow meter for liquid 36
Employs an ultrasonic flow meter so as not to disturb the flow of the supplied cleaning liquid. This ultrasonic flow meter is provided with a pipe 21b.
A detector (alternately a transmitter or a receiver) is attached to the upstream side and the downstream side of, and an ultrasonic pulse is propagated between both detectors by a reflection method, and the propagation time is measured alternately. The flow rate is measured by utilizing such a difference. Also,
The gas supply pipe 22 includes a pipe 22a having both ends connected to corresponding ends of the gas injection pipe 23, and a pipe 22b connecting the gas supply source and the pipe 22a. The pipe 22b is provided with a gas shut-off valve 34 on the pipe 22b side, and a gas pressure gauge 37 and a gas flow meter 38. On the other hand, in the liquid discharge pipe 23, an automatic drainage valve (a valve that performs only the opening / closing operation) 31 is provided on the drainage port 2 side, and a normally-closed automatic valve (closed when the electricity is turned off) is provided downstream thereof. Type solenoid valve or pneumatic valve 32 is provided. A bypass pipe 23a is provided with the drainage automatic valve 31 interposed therebetween, and a bypass valve 33 is attached to the bypass pipe 23a. Although omitted in the drawing, the water collecting section 6 is connected to a liquid discharge pipe at a discharge port provided at an appropriate position.

(Control Mechanism) The rinsing tank 1 includes a valve power supply 24 and an interface 2 as a main drive mechanism.
5, a control device 27A, and a monitoring device 27B. The valve power supply 24 receives, for example, a valve opening / closing signal sent from the control device 27A via the communication line 24a and an abnormal signal sent from the monitoring device 27B via the communication line 24b.
The corresponding valves such as 0a, 30b, 31, 32, 33 or all the valves are opened or closed according to the signal. The interface 25 is a circuit that converts a one-contact signal into a two-contact signal that is electrically insulated and outputs the signal (ie, substantially the same as a one-input, two-output buffer). Specifically, the water level signal 2 transmitted from the external processing units 16a and 16b corresponding to the respective water level gauges 15a and 15b
6a, 26b (26), the valves 30a, 30b, 31,
The valve opening / closing signal 28 transmitted from 32, 33 or the like is converted into a format suitable for the control device 27A and the monitoring device 27B, and the water level signal 26 and the valve opening / closing signal 28 are converted to the control device 2
7A and the monitoring device 27B. The control device 27A controls the operation of the rinsing tank 1, and at least the water level signal 26,
A valve opening / closing signal 28 is received, and a valve control signal 29 is sent to each of the valves 30a, 30b, 31, 32, 33 and the like by built-in program processing to perform opening / closing control. Monitoring device 27B
Operates independently of the control device 27A, receives the water surface signal 26 and the valve opening / closing signal 28 from the contact signal interface 25, and outputs the liquid pressure gauge 35 and the liquid flow meter 36, the gas pressure gauge 37 and the gas flow meter Data is received from each of the rinsing tanks 38, and based on them, it is possible to cope with an abnormal situation of the rinsing tank 1 described later.

Next, the operation of the above control mechanism will be described with reference to an example of cleaning control performed in actual semiconductor manufacturing. Here, an example will be described in which the wafer c is cleaned with a chemical solution in the previous process, and the wafer c is cleaned with pure water by a wafer cleaning apparatus using the rinsing tank 1, but the same applies to the chemical solution cleaning.

(Cleaning Control Example-1. Operation During Standby) In the above-described wafer cleaning apparatus, first, when there is no plan to send the cassette 20 after the chemical cleaning to the rinsing tank 1,
Alternatively, when the waiting time is long, the automatic drain valve 31 for drainage, the normally closed automatic valve 32, and the automatic valves 30a and 30b for supply liquid are closed by the control of the control device 27A, and the automatic valve of the bypass pipe 21c is closed. 30d is opened and a small amount of pure water is supplied from the needle valve 30c to the tank cleaning unit 1A from the liquid introduction unit 10a, and is drained from the overflow drain unit 5 so that the chemical solution or pure water in the waiting state, i.e., the idling state. Save water consumption. In addition, when the cleaning of the chemical solution in the previous process is completed and the cassette 20 is sent to the rinsing tank 1, the supply liquid automatic valve 30 a and the normally-closed automatic valve 32 are opened in advance, and the supply liquid automatic valve 30 a is opened. When the valve 30b, the automatic drainage valve 31, and the automatic valve 30d are closed, the pure water supplied from the liquid supply pipe 21 flows into the liquid introduction part 10a from the supply port 4a, passes through the hole in the punching side plate 7a, and is rinsed. Is supplied to the tank washing section 1A, a part of which is turned into a downward water flow from the hole of the punching lower plate 8 to the discharge port 2 and the bypass valve 33.
Through the liquid discharge pipe 23, and the remaining part becomes the horizontal surface water flow and is drained from the overflow drain part 5, and waits for the arrival of the cassette 20.

(Cleaning control example-2. Operation at the time of setting) When four cassettes 20 arrive at the rinsing tank 1 and descend for the first time toward the corresponding cradle 11, they enter the control unit 2
In response to the control signal from 7A, the gas shutoff valve 34 is opened, and a nitrogen gas having a desired flow rate is jetted out of the gas jetting pipe 13 into the tank by the gas flow meter 38, and the pure water in the rinsing tank 1 is vigorously stirred. The chemical solution attached to each cassette 20 and the wafer c stored therein is mixed with the entire pure water in the tank,
Pure water mixed with the chemical solution while its concentration is rapidly reduced is discharged from the overflow drain section 5. Thus, the cassette 20 and the wafer c stored therein are
The cleaning solution adhering to the surface is rapidly diluted and quenched, and at the same time, the rinsing effect is enhanced. In particular, in the case of etching an oxide film with dilute hydrofluoric acid, the dilute hydrofluoric acid adhering to the wafer is rapidly thinned and the etching action is stopped instantaneously, so that the uniformity of the oxide film etching can be improved.

(Example of cleaning control-3. Cleaning operation after setting)
When the four cassettes 20 are set on the pedestal 11, the gas cutoff valve 34 is closed by a control signal from the control device 27A. When the high water level gauge 15a set slightly below the overflow drain section 5 detects the water level, a water level signal 26a output from the external processing section 16b is sent to the control device 27A via the contact signal interface 25. Then, the control device 27A generates a valve control signal 29 based on the water level signal 26a, and the supply liquid automatic valve 30a
Is closed, the supply liquid automatic valve 30b and the drainage automatic valve 31 are opened, and the supply port 4b and the liquid introduction section 10 are opened from the automatic valve 30b.
Through b, the supply of pure water is continued from the hole of the punching side plate 7b, but the amount of drainage discharged from the discharge port 2 exceeds that, and the water surface starts to lower. At this time, a vortex starts to be generated in the rinsing tank 1, but the water level immediately drops to a position where the low water level gauge 15b detects the water level, and the water level signal 2
6b is sent to the control device 27A via the contact signal interface 25, the automatic drainage valve 31 is closed, the descent of the water surface is stopped, and the generated eddy current is extinguished by stopping the supply of energy. In this way, the supplied pure water causes the solution in the rinsing tank 1 to be drained out of the drain port 2 as a laminar flow without mixing, and the rinsing tank 1 is rapidly filled with pure water. Will be replaced. Next, when the high water level gauge 15a detects the water level, the automatic valve 30b is closed, the automatic valve 30a is opened, pure water is supplied from the punching side plate 7a, and at the same time, the automatic drainage valve 31 is opened. Again, the water surface begins to descend. In this manner, the automatic valves 30a and 30b are alternately opened and closed, the punching side plates 7a and 7b, that is, the left and right alternately, are supplied to the tank cleaning unit 1A of the rinsing tank 1 alternately, and drainage is performed in a laminar flow. Each cassette 20 and the wafers c stored therein can be rinsed uniformly and efficiently.

(Example of cleaning control-4. Operation of final stage of cleaning)
In the final stage of such a rinsing operation, the automatic valve 3 is always used.
0a is opened, the automatic valve 30b and the automatic drain valve 31 are closed, the pure water overflows from the overflow drain 5 and the floating substances floating on the water surface are washed away, and then each cassette 20 is removed from the rinse tank 1. Take out. By doing so, the cassette 20 and the wafer c, for which rinsing has been completed, are removed from the risk of adhesion of floating substances floating on the water surface when being taken out of the rinsing tank 1.

(Washing control example-5. Operation of monitoring device) The same water level signal 26 sent to the control device 27A is transmitted to the monitoring device 27B via the contact signal interface 25, and the high water level gauge 15a Is the time T1 from when the water level is detected to when the low water level gauge 15b detects the water level, and the low water level gauge 15 after the automatic drainage valve 31 is opened.
b is the time T2 until the water level is detected, and the integrated value V1 of the supply flow rate measured by the liquid flow meter 36 during that time, from the time when the low water level gauge 15b detects the water level to the time when the automatic drainage valve 31 is closed. At a time T3, a time T4 from when the automatic drainage valve 31 is closed to when the high water level gauge 15a detects the water surface and an integrated value V2 of the supply flow rate measured by the water flow meter 24 are measured and monitored. At the same time, it is recorded in the memory of the memory 27B, and is statistically processed. From the average and the variance, it is determined from what time it is the same. Here, the occurrence of abnormalities expected in the embodiment of the present invention and the corresponding measures will be described. In this embodiment, since the water is drained from the drain port 2 provided at the bottom of the rinsing tank 1 and the discharge amount is larger than the pure water supply amount, the low water level gauge 15b may malfunction or the drainage automatic valve 31 When a failure occurs in which the water cannot be closed, the pure water surface (water level) continues to drop, the wafer c is exposed, the attached solution evaporates, and the residue of the non-volatile components dissolved therein precipitates on the wafer surface. Contamination, such as fine dust, and dust floating in the air. As such defects, four causes are supposed: first, power failure, second, decrease and stop of pure water flow, third, malfunction of the water surface detection sensor, and fourth, malfunction of the automatic drainage valve 31. Next, measures for preventing the wafer c from being exposed from the water surface in the embodiment for these causes will be described.

In the case of the first power failure, the automatic valve 32 is a normally-closed valve, so that it automatically closes during a power failure, and the drainage from the drain port 2 of the rinsing tank 1 stops immediately.
The water surface does not drop. Therefore, the wafer c is not exposed from the water surface due to the power failure. Valve power supply 2
4 is that once power is cut off by power failure or emergency stop signal,
"Power OFF safety mode" where power is not automatically turned on unless the operator presses the return button, even if power failures spread.
Specifications (Hiroyuki Harada, "Safety Measures in Semiconductor Manufacturing", Handbook for Safety Measures and Management in Semiconductor Manufacturing, p.1 (1993, published by Realiz Ltd.)).

When the second pure water flow rate decreases or stops,
When the pure water flow rate measured by the water flow meter 36 monitored by the monitoring device 27B falls below a predetermined value,
Since a signal for emergency stop of the valve power supply 24 is sent from the emergency stop communication line 24b and the power supply of the valve power supply 24 is shut off, the normally closed automatic valve 32 is closed, and drainage from the rinse tank 1 is stopped, The wafer c is prevented from being exposed from the water surface.

A countermeasure against the third water surface sensor malfunction will be described. When the drainage flow rates from the automatic drainage valve 31 and the bypass valve 33 are f (31) and f (33), respectively, and the pure water supply flowrate from the supply ports 4a and 4b is f, the normally-closed automatic valve 32 is opened. The time Td at which the water level drops from the high water level gauge 15a to the low water level gauge 15b
Is obtained from the following equation (1): V = (f (31) + f (33)) · Td−∫f · dt (1) Here, V is the high water level gauge 15a.
, The volume of the rinsing tank 1 from the low water level gauge 15b to the low water level gauge 15b, and ∫ is the integral between 0 and Td. V, f (31),
f (33) is a device constant and is assumed to be known. Since f can be measured by the liquid flow meter 36, the monitoring device 27B can calculate Td using Expression (1). Therefore, when the normally closed automatic valve 32 is opened and the high water level gauge 15a detects the water level, and the signal indicating the detection of the water level is not transmitted from the low water level gauge 15b even after the time Td, the monitoring is performed. An emergency signal is sent from the device 27B to the valve power supply 24, and all the valves 30a, 30b, 31, 32, 3
3 is closed to prevent the wafer c from being exposed from the water surface.

When the normally-closed automatic valve 32 is closed,
The time Tu at which the water surface rises from the low water level gauge 15b to the position of the high water level gauge 15a is given by the following equation (2): V = ∫f · dt-f (33) · Tu (2) ). Here, ∫ is an integral between 0 and Tu. Therefore, if the high water level gauge 15a does not transmit a signal indicating that the high water level gauge 15a has detected the water level even after Tu time has elapsed since the low water level gauge 15b detects the water level after the automatic drainage valve 31 is closed, the monitoring device 27B Sends an emergency signal to the valve power supply 24 to shut off the operation, and all valves 30a, 30b, 31,
32, 33, etc. are closed.

In the above description, either the low water level gauge 15b or the high water level gauge 15a has missed the water level detection, and Td and Td calculated by the equations (1) and (2) are used.
Low water level gauge 15b or high water level gauge 1 after u time has passed
If 5a fails to detect the water surface, immediately the valve power supply 2
4 was emergency-stopped, but a signal was sent from the monitoring device 27B to the control device 27 instead of the low water level gauge 15b and the high water level gauge 15a, and the opening and closing of the automatic drainage valve 31 was controlled by this signal. The rinsing process may be continued. Further, even if both the low water level gauge 15b and the high water level gauge 15a cannot detect the water level on the way, the rinsing can be continued. In addition, the monitoring device 27B continues until the time obtained by adding the grace time Ty to the Td and Tu times elapses.
There is also a method that does not output an emergency signal from. Either method can prevent the wafer c from being exposed from the water surface.

In the case of a failure in which the fourth automatic drain valve 31 cannot be closed, for example, the water level falls due to the opening of the automatic drain valve 31 and the controller 27A detects the water level after the low water level gauge 15b detects the water level. A close signal is output to the automatic drainage valve 31 and, due to a time delay until the automatic drainage valve 31 is actually closed,
Although the water level further lowers than the low water level gauge 15b, when the automatic drainage valve 31 is closed, the water level starts to rise, and the water level passes through the low water level gauge 15b again. First, the time T1 from when the water surface descends to the low water level gauge 15b until the water surface passes again is almost constant. Therefore, after the first passage, the water surface is within a time period T1 plus a margin. If no emergency signal can be detected, an emergency signal is sent from the monitoring device 27B to the valve power supply 24, and all the valves 30a, 30b, 31, 32, 3
Even if 3 etc. are closed and automatic drainage valve 31 does not close,
The drainage from the drainage port 2 can be closed by the normally-closed automatic valve 32.

(Operation of Rotation Driving Means) Rotation Driving Means 17
Rotates and rotates the wafer c in the cassette 20 up and down by the rotation of the rotating rod 19.
The solution in a is replaced to improve the rinsing effect, and the difference between the rinsing effect and the etching rate in the vertical direction is leveled, thereby improving the uniformity. Further, the solution in the rinsing tank 1
Since the particles flow toward the lower drain port 2, even if particles are generated with the rotation of the rotating rod 19, the particles are quickly discharged from the drain port 2, and the contamination of the wafer c can be reliably prevented.

(Wafer Cleaning Apparatus Using Rinse Tanks 40A and 40B) In this wafer cleaning apparatus, as shown on the left side of FIG. 4, a wafer c is sequentially placed in at least a first rinse tank 40A and an adjacent second rinse tank 40B. It is a compound type that is put in and washed, and the features of the device are as follows. That is, each rinsing tank 40
A and 40B are required to be formed of a so-called OFR tank, which supplies pure water from a supply port 41 provided at the bottom of the tank and overflows and discharges the pure water in the tank from the top of the tank. At the same time, the arrangement of both rinsing tanks 40A and 40B is
It is essential that the rinsing tank 40A be installed with a step so as to be lower than the second rinsing tank 40B. And
In this structure, the outlet 43 of the water collecting part 42 for storing the pure water overflowing from the second rinsing tank 40B and the supply port 41 of the first rinsing tank 40A are connected by a pipe 44, and the second rinsing tank 40B The pure water overflowing to the water collecting section 42 is introduced into the first rinsing tank 40A due to the difference in water level between the two rinsing tanks 40A and 40B. Therefore, in this wafer cleaning apparatus, pure water supplied from the supply unit 41 to the second rinsing tank 40B, that is, used for final cleaning, overflows from the second rinsing tank 40B and is collected in the water collecting unit 42. Pure water
It is automatically supplied to the supply port 41 of the first rinsing tank 40A through the pipe 44, and is used again in the first rinsing tank 40A. In this manner, in this structure, for example, the first rinse tank 40A for cleaning the wafer c that has been subjected to the chemical liquid cleaning or the initial pure water cleaning with the pure water used in the second rinse tank 40B that is the final cleaning. By using it, the consumption of pure water can be reduced by half, and in addition, continuous transfer can be realized without requiring liquid transfer power such as a pump and ancillary equipment.

In the above description of the embodiment, an example has been described in which pure water is put into each of the rinsing tanks 1, 40A, 40B and rinsing is performed sequentially. No problem. In this case, in FIG. 4, the rinsing tank 1 is used for cleaning the chemical solution, and the rinsing tanks 40A, 40
OB is configured for pure water cleaning.

[0036]

As described above, by adopting each wafer cleaning apparatus of the present invention, cleaning and rinsing can be efficiently performed even in a mass production line for simultaneously rinsing a total of four wafer cassettes arranged in two rows. Since the chemical solution adhering to the cassette at the start of rinsing and the wafers stored in the cassette can be efficiently diluted, a uniform cleaning rinsing effect can be obtained, and the cleaning effect is improved, so that pure water can be conserved and cleaned. It is possible to realize excellent wafer cleaning equipment, such as shortening the time and avoiding irreparable damage and contamination of the wafer even if a sudden power failure or abnormal water level detection occurs.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a wafer cleaning apparatus shown as an embodiment of the present invention.

FIG. 2 is a configuration diagram showing details of a rinsing bath of FIG. 1;

FIG. 3 is a diagram showing an operation of a rotary drive unit of the rinsing tank.

FIG. 4 is a schematic configuration diagram showing the entire wafer cleaning equipment to which the present invention is applied.

[Explanation of symbols]

1 is a rinse tank (1A is a tank cleaning section) 2 is a discharge port 3a, 3b is a side wall 4a, 4b facing the tank 4 is a supply port 5 is an overflow drain section 6, 42 is a water collecting section 7a, 7b is a punching side plate 8 Lower punching plates 10a and 10b are liquid introduction portions 13 are gas injection pipes (gas injection means) 15a and 15b are high and low water level gauges 17 are rotary drive means (19 is a rotating rod) 20 are cassettes 30a and 30b , 31, 32, 33 are valves (32 is a normally closed automatic valve) 23a is a bypass pipe 25 is an interface 27A is a control device 27B is a monitoring device 35, 37 is a pressure gauge 36, 38 is a flow meter (36 is an ultrasonic flow rate) 40A is the first rinsing tank 40B is the second rinsing tank 41 is the supply port 42 is the water collecting section 44 is the connecting pipe

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuyuki Morishima, Inventor 1-6-1, Kanda Jimbocho, Chiyoda-ku, Tokyo Inside Nisso Engineering Co., Ltd. (72) Inventor Akira Yoneya 1-6-1, Kanda Jimbocho, Chiyoda-ku, Tokyo No. Nisso Engineering Co., Ltd. (72) Inventor Yatsukatsu Nishikata 1-6-1, Kanda Jimbocho, Chiyoda-ku, Tokyo Nisso Engineering Co., Ltd. (72) Inventor Toshimitsu Kachi 1-6-1, Kanda Jimbocho, Chiyoda-ku, Tokyo No. Nisso Engineering Co., Ltd. (72) Inventor Takao Nakazawa 1-29-28-28 Zenpukuji, Suginami-ku, Tokyo F-term (reference) 3B201 AA03 AB33 AB40 AB44 BB02 BB03 BB04 BB88 BB93 CB15 CC01 CD42 CD43

Claims (11)

[Claims] 1. A wafer cleaning apparatus used in a semiconductor manufacturing process, in which a wafer is placed in a rinsing tank having a discharge port at the bottom of the tank and is washed, wherein the rinsing tank is provided with a gap between opposing side walls. It is provided with a punching side plate provided, and a liquid introduction portion extending up and down the tank is formed in a pair between the punching side plate and the corresponding side wall, and a cleaning liquid is supplied to the liquid introduction portion from a lower supply port, A wafer cleaning apparatus, wherein the wafer is introduced into a tank cleaning unit through a hole in the punching side plate. 2. The wafer cleaning apparatus according to claim 1, further comprising an overflow drain having an upper end of one of the opposed side walls lowered together with the outlet. 3. The wafer cleaning apparatus according to claim 1, wherein a cleaning liquid is supplied to the two liquid introduction sections via respective valves. 4. The wafer cleaning apparatus according to claim 1, further comprising a normally-closed automatic valve which is provided on the discharge port side and is closed when electricity is cut off. 5. The wafer cleaning apparatus according to claim 1, further comprising a gas injection unit disposed below the inside of the tank and capable of ejecting a gas such as nitrogen gas. 6. The wafer cleaning apparatus according to claim 1, further comprising an ultrasonic flowmeter as a unit for measuring a flow rate of the cleaning liquid introduced into the liquid introduction unit and the tank cleaning unit. 7. A wafer cleaning apparatus used in a semiconductor manufacturing process for cleaning a wafer by placing the wafer in a rinsing bath, wherein the rinsing bath includes a supply port for introducing a cleaning solution into the bath via a valve, and a cleaning solution in the bath. A discharge port that discharges through a valve, a unit that can detect the water surface in the tank and transmit it as a water surface signal, and a control device that controls opening and closing of the valve with the water surface signal,
A monitoring device that monitors at least the water level signal and opens and closes the valve independently of the control device. 8. When a one-contact signal is input, at least the water surface signal and the valve opening / closing signal of the valve are converted to an electrically insulated two-contact signal via an interface that outputs the signal. 8. The wafer cleaning apparatus according to claim 7, wherein the wafer cleaning apparatus can transmit the data to the monitoring apparatus. 9. A wafer cleaning apparatus used in a semiconductor manufacturing process for cleaning a wafer by placing it in a rinsing tank, wherein the rinsing tank removes a plurality of wafers in a cassette placed in the tank while being aligned and accommodated. A wafer cleaning apparatus, comprising: a rotation drive unit that rotates. 10. The wafer cleaning apparatus according to claim 8, wherein the rotation driving means receives the wafer in the cassette from below by means of a rotating rod having an elliptical vertical section and rotates and swings up and down. 11. A wafer cleaning apparatus used in a semiconductor manufacturing process for cleaning a wafer by sequentially placing at least a wafer in a first rinsing bath and a second rinsing bath, wherein the first rinsing bath and the second rinsing bath are provided at the bottom of the bath. Pure water is supplied from the supply port provided, and the pure water in the tank overflows from the upper part of the tank and is discharged, and the first rinse tank has a step so as to be lower than the second rinse tank. A discharge port of a water collecting section that houses the pure water that is juxtaposed and overflows from the second rinsing tank and a supply port of the first rinsing tank are connected by a pipe, and a water collecting section of the second rinsing tank is connected. Wherein the pure water overflowing into the first rinsing tank is introduced into the first rinsing tank by a water level difference caused by a step between the two rinsing tanks.