JP4565718B2 - Wafer cleaning equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a wafer cleaning apparatus suitable for a cleaning process for cleaning a wafer with a chemical solution or pure water in a semiconductor manufacturing process. In the present specification, “chemical solution and pure water” are collectively referred to as a cleaning solution unless particularly required to be distinguished.
[0002]
[Prior art]
  Cleaning processes in semiconductor manufacturing include cleaning using a high-temperature mixture of sulfuric acid and hydrogen peroxide to remove organic contaminants, cleaning using a high-temperature mixture of hydrochloric acid and hydrogen peroxide to remove heavy metal contamination, and fine particles There is a cleaning using a mixed solution of ammonia and hydrogen peroxide for the purpose of decontamination. In actual wafer manufacturing, these cleanings are used alone or in combination depending on the contamination status of the wafer and the wafer process. As the etching process, silicon oxide film etching with buffered hydrofluoric acid and silicon nitride film etching with hot phosphoric acid are widely used. In wafer cleaning (including etching) with these chemical solutions, after the wafer processing with the chemical solution is completed, the cleaning process is continuously performed with pure water, and then the cleaning is started with another chemical solution. In this way, a combination of the treatment with the chemical solution and the subsequent treatment with pure water constitutes a unit process for wafer cleaning. In actual wafer cleaning, several such unit processes are combined.
[0003]
  In the semiconductor manufacturing process, the wafer cleaning is repeatedly performed so that “starts with cleaning and ends with cleaning”, so that a large amount of pure water is consumed. In one theory, per 200mm waferabout6 tons of pure water is required, and 300 mm wafers that will become full-scale in the future will further increase the consumption of pure water, and measures to save pure water are required. In recent years, energy consumption has been required to be reduced in order to reduce carbon dioxide emissions, which are a cause of global warming. However, it is said that about 20 kWh of electricity is required per ton of pure water production. Therefore, reduction of pure water consumption is also strongly demanded from the viewpoint of global warming prevention.
[0004]
  As described above, in order to satisfy the demand for reducing pure water consumption, pure water can be used effectively by improving the rinsing efficiency in the rinsing tank that consumes most of the pure water in semiconductor manufacturing. A rinsing tank that can drastically reduce consumption, that is, an apparatus structure in which pure water is introduced from above one side of the tank to form a lower water flow and an overflow water flow has been invented (Japanese Patent No. 20133691). 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, which has been widely used in the past, and is overflowed from the upper part, this invention allows rapid replacement of 40% or more of pure water. Rinse (hereinafter referred to as QCR) tank has been developed (Miyakoshi, et al., “QC Cleaning-New Wafer Cleaning by Rapid Replacement Method in Cleaning Rinse Tank”, Proceedings of the 16th Annual Conference on Air Cleaning and Contamination Control, p.216 (1999), Miyakoshi, et al. "QC cleaning-New wafer cleaning by rapid replacement method in cleaning rinse bath (3)" Proceedings of the 18th Air Cleaning and Contamination Control Research Conference, p. 95, (2000).
[0005]
[Problems to be solved by the invention]
  The above-mentioned QCR tank is rapidly stirred with pure water supplied with the solution in the tank so that the pure water supplied with less generation of the vortex flow generated in the rinse tank and the solution in the tank are not stirred and mixed. Since it can be replaced, the chemical solution attached to the wafer and wafer cassette transferred to the rinsing tank after the chemical treatment is mixed with the pure water previously stored in the rinsing tank, and the action of diluting is weakened. In this state, rinsing was started, and the rinsing efficiency was reduced accordingly. Fortunately, the improvement in the rinsing efficiency of the QCR tank is good enough to drastically drop compared to 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 adhesive chemical solution at the start of rinsing weakens the quenching effect in the rinsing of oxide film etching with dilute hydrofluoric acid or the like, and thus etching variation is a problem. In addition, since the conventional QCR tank supplies pure water only from one side, in a mass production wafer cleaning apparatus that simultaneously cleans two cassettes in two rows, a total of four cassettes, the pure water supply side and the opposite side There was a difference in the rinsing effect, and the rinsing time was increased correspondingly, and the decrease in pure water / water saving effect was a problem. Also, in the QCR tank that drains from the bottom of the tank, the surface of the rinse tank drops until the wafer is exposed from the water surface due to a sudden power outage, deionized water supply failure, or malfunction of the water level meter, and adheres to the exposed wafer surface. It was also a problem that the solution that had been evaporated evaporates and the evaporation residue becomes fine particles, causing particle contamination, and irreparably damaging the wafer.
[0006]
  The present invention solves the problems of the conventional QCR tank as described above, enables efficient wafer cleaning with a small amount of pure water or chemicals, has excellent etching and rinsing uniformity, and prevents sudden abnormalities. Another object of the present invention is to provide a highly reliable wafer cleaning apparatus that does not cause recoverable damage to the wafer.
[0007]
[Means for Solving the Problems]
  The present invention has been devised in order to achieve the above-described object.
  The invention of claim 1 is used in a semiconductor manufacturing process as illustrated in FIG. 2 and the like, and in the wafer cleaning apparatus for cleaning the wafer c by putting the wafer c in a rinse tank 1 having a drain port 2 at the bottom of the tank, the rinse tank 1 Are provided with a gap between the opposing side walls 3a and 3b, respectively.Punching side plates 7a, 7b forming liquid introducing portions 10a, 10b extending vertically from the corresponding side walls to the corresponding side walls, and a liquid supply pipe 21 for the cleaning liquid provided below each liquid introducing portion, respectively. Supply ports 4a and 4b to be connected, and valves 30a and 30b respectively provided in portions near the respective supply ports of the liquid supply pipe 21;The cleaning solution iseachLiquid introduction part10a and 10b can be alternately supplied from the liquid supply pipe 21 through the valves 30a and 30b and the supply ports 4a and 4b, and the liquid introduction portions are formed.It is characterized by being introduced into the tank cleaning section 1A through the holes 7a and 7b.
  In this structure, the liquid introduction portions 10a and 10b which are on both sides and extend in the vertical direction of the tank are partitioned by the punching side plates 7a and 7b, so that the cleaning liquid is alternately supplied from the holes of the punching side plates 7a and 7b to the tank cleaning portion 1A. It becomes possible. In addition, the cleaning liquid is supplied to the tank cleaning unit 1A from a plurality of holes on the punching side plates 7a and 7b on both sides. For example, when the tank is filled, the horizontal water flow is exclusively supplied from the holes on the uppermost stage of the punching side plates 7a and 7b. Since it is introduced into the tank cleaning unit 1A, it becomes possible to form an overflow water surface flow.
[0008]
  In additionThe invention of claim 5The wafer cleaning apparatus according to claim 1, whereinAs illustrated in FIG.The opening / closing of the valves 31, 32, 33 provided on the discharge port side and the valves 30a, 30b, etc. provided on the supply ports is controlled by a water level signal when a water level or a water level in the rinse tank is detected. It is a configuration.
[0009]
[0010]
[0011]
DETAILED DESCRIPTION OF THE INVENTION
  Next, embodiments 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. 1 is a schematic configuration diagram mainly showing a rinsing tank drive system used initially in the cleaning equipment of FIG. 2A is a schematic configuration diagram of the rinse tank of FIG. 1 as viewed from above, and FIG. 2B is a cross-sectional view taken along line AA of FIG. FIGS. 3A and 3B are schematic views showing the operation of the rotation driving means of the rinsing tank in the cross section taken along line BB in FIG. 2A.
[0012]
  The cleaning equipment of FIG. 4 is a configuration example in which the chemical-cleaned wafer c is cleaned with pure water in the rinse tank 1 and then cleaned with pure water in order by the other first rinse tank 40A and the second rinse tank 40B. is there. here,Although the wafer cleaning apparatus mainly composed of the cleaning bath 1 is premised on pure water cleaning, it can also be used for chemical cleaning. On the other hand, the first and second rinsing tanks 40A and 40B exclusively perform pure water cleaning. However, in principle, it may be a chemical solution.
  And in relation to the present invention, claims 1 to5The wafer cleaning apparatus according to the present invention has a configuration related to the rinsing tank 1.Has identifiedThe
[0013]
(Wafer Cleaning Apparatus Using Rinsing Tank 1) This wafer cleaning apparatus is mainly composed of a mass-production type rinsing tank 1 that simultaneously cleans a total of four wafer cassettes 20 in two rows as shown in FIGS. The tank structure and its control mechanism are devised. Next, main device structure features will be described in detail.
[0014]
(Tank structure) The rinsing tank 1 includes punching side plates 7a and 7b that define liquid introduction portions 10a and 10b between the discharge port 2 and the side walls 3a and 3b provided at the bottom of the tank, and the upper ends of the one side walls 3b. The overflow drainage section 5 having a lowered height, a punching lower plate 8 disposed on the lower side in the tank, a gas injection means comprising two pipes 13 disposed in the gap between the punching lower plate 8 and the tank bottom surface, Rotation driving means for rotating and vertically swinging the wafers c aligned and accommodated in the water level gauges 15a and 15b and the cassette 2017Etc.
[0015]
  In FIG. 2, the rinsing tank 1 has a substantially rectangular container shape with the side walls 3a and 3b and the side walls 3c and 3d facing each other and the lower side being partitioned by a gentle V-shaped bottom wall 3e. . The side wall 3b is set slightly lower than the side wall 3a, and the upper end forms the overflow drainage portion 5. A water collecting portion 6 is attached to the outside of the side wall 3b. The water collection unit 6 is a place that receives and drains the cleaning liquid overflowing from the overflow drainage unit 5. 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, respectively. The punching side plates 7a and 7b and the punching lower plate 8 have a plurality of holes provided on the upper, lower, left and right sides for passing the cleaning liquid. The punching side plates 7a and 7b are detachably held by the clamping members 9 on the opposing inner surfaces of the side walls 3c and 3d and fixed in the vertical direction, and extend vertically between the corresponding side walls 3a and 3b. 10a and 10b are formed. Note that 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 portions 10a and 10b communicate with the corresponding supply ports 4a and 4b. On the other hand, the punching lower plate 8 is installed on the corresponding convex portion of the bottom wall 3e, and forms 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 cradle 11 has a frame shape for positioning and holding the cassette 20. The bearing member 12 pivotally supports a rotating rod 19 of a rotation driving mechanism 17 described later. Accordingly, the inside of the rinsing tank 1 forms a tank cleaning portion 1A by the side walls 3c and 3d, the punching side plates 7a and 7b, and the punching lower plate 8. The tank cleaning unit 1A is supplied with cleaning liquid from the supply ports 4a and 4b to the liquid introduction units 10a and 10b, and is supplied from there through a plurality of holes in the punching side plates 7a and 7b. In this liquid supply mode, the cleaning liquid is smoothly supplied as a flat water flow through a hole having a height corresponding to the amount of water in the tank among the holes of the punching side plates 7a and 7b on both sides. The cleaning liquid in the tank is discharged from the lower drainage port 2 and can also be discharged from the upper overflow drainage part 5 when the tank cleaning part 1A is full. In this liquid discharge mode, local deviation of the liquid portion discharged from the discharge portion 2 is eliminated due to the presence of the punching lower plate 8, and foreign matter floating on the water surface in the tank is washed away due to the presence of the overflow drainage portion 5. It is possible to form a clean water surface without foreign matter. The punching side plates 7a and 7b can be formed integrally with the rinsing tank 1. However, when the punching side plates 7a and 7b are detachably assembled via the holding member 9, the punching side plates 7a and 7b have excellent maintainability and versatility.
[0016]
(Gas injection means and water level meter) The piping 13 has small holes opened along the upper longitudinal direction, and injects nitrogen gas or the like to the tank cleaning unit 1A through the punching lower plate 8. The pipe 13 is bent corresponding to the left and right cradle 11 and is held by the support member 14 on the inner surface side of the bottom wall 3e. 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 means. The water level gauges 15a and 15b are installed at an appropriate position in the tank by a retrofitting method. The water level gauge 15a is a high water level gauge, and detects the state immediately before the cleaning liquid is filled in the tank and overflows from the overflow drainage section 5. The water level gauge 15b is a low water level gauge and detects the state when the cleaning liquid is in the tank and the cassette 20 is filled. The detection values of the water level gauges 15a and 15b are sent to the external processing units 16a and 16b installed outside the rinsing tank 1 via signal lines, and are signal processed to the contact signal interface 25 as water surface signals 26a and 26b. Sent.
[0017]
(Rotation drive means) The rotation drive means 17 rotates and swings up and down a plurality of wafers c in the cassette 20 simultaneously with the cassette 20 positioned and held on the cradle 11. In this example, the rotary power unit 18 is provided outside the side wall 3d, and the rotary rod 19 is pivotally supported by the bearing member 12 described above. The rotational power unit 18 is composed of a motor or the like. The rotating rod 19 is provided with a cylindrical member 19b having an elliptical cross section around the axis of a perfect circular shaft 19a. 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 has a proximal end connected to the rotational power unit 18, and is rotated integrally with the cylindrical member 19b by driving the rotational power unit 18. Note that the cassette 20 has a plurality of opposed vertical grooves 20a as in the prior art, and has a structure in which a large number of wafers c are regularly arranged in the vertical grooves 20a.
[0018]
  When the wafer cleaning apparatus has the rotation driving means 17 described above, when the cassette 20 is held on the cradle 11, the wafer c in the cassette 20 is supported on the elliptical cylindrical member 19 b of the rotating rod 19. In this set state, when the rotary rod 19 is rotated by the rotary drive means 17, the wafer c is shown in FIG.3 (While being rotated in the vertical groove 20a as shown in a) to (b), it is swung up and down along the vertical groove 20a according to the degree of elliptical deformation. This advantage eliminates variations in the degree of cleaning and etching that are likely to occur at the upper and lower portions of the wafer c during the chemical or pure water cleaning process, and improves uniform cleaning and etching. The larger the diameter of the wafer c, the more remarkable the improvement effect. Become. If the wafer c is not rotated as in the prior art, a portion of the outer peripheral portion of the wafer c located in the vertical groove 20a is not cleaned or etched, but such a problem can be solved.
[0019]
(Supply / Discharge Pipe Line Configuration) The rinse tank 1 is connected to liquid supply pipes 21 for sending pure water or chemicals to the supply ports 4a and 4b as shown in FIG. A gas supply pipe 22 for sending the gas is connected, and a liquid discharge pipe 23 is connected to the discharge port 2.
  Among these, the liquid supply pipe 21 includes a pipe part 21a having both ends connected to the supply ports 4a and 4b, and a pipe part 21b connecting the liquid supply source and the pipe part 21a. Automatic valves (valves that only perform opening and closing operations) 30a and 30b are attached to both sides of the pipe portion 21a, that is, portions close to the supply ports 4a and 4b. tubePart 21a, a bypass pipe 21c is provided on the supply port 4a side with an automatic valve 30a interposed therebetween, and a needle valve (flow rate adjusting valve) 30c and an automatic valve (a valve for performing only an opening / closing operation) 30d are attached to the bypass pipe 21c. Has been. A liquid pressure gauge 35 and a liquid flow meter 36 are attached to the pipe portion 21b. The liquid flow meter 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 detectors (alternately transmitters or receivers) on the upstream side and downstream side of the tube portion 21b, and propagates ultrasonic pulses between both detectors by a reflection method. The propagation time is measured alternately, and the flow rate is measured using the difference. The gas supply pipe 22 has gas injection pipes at both ends.13The pipe part 22a is connected to the corresponding end of the gas pipe, and the pipe part 22b is connected to the gas supply source and the pipe part 22a. tubePart 22b, tubePart 2A gas shut-off valve 34 is attached to the 2b side, and a gas pressure gauge 37 and a gas flow meter 38 are attached. On the other hand, the liquid discharge pipe 23 is provided with a drain automatic valve (a valve that performs only an opening / closing operation) 31 on the drain outlet 2 side, and is normally closed on the downstream side (closed when electricity is turned off). Type solenoid valve or pneumatically operated valve) 32 is attached. Further, a bypass pipe 23a is provided across the automatic drain valve 31, and a bypass valve 33 is attached to the bypass pipe 23a. Although not shown in the drawing, the water collecting part 6 is connected to a liquid discharge pipe at a discharge port provided at an appropriate position.
[0020]
(Control Mechanism) The rinse tank 1 includes a valve power source 24, an interface 25, a control device 27A, and a monitoring device 27B as a main drive mechanism. For example, the valve power supply 24 is configured to detect the valve 30a, 30b, 31, 32, 33 or the like by a valve opening / closing signal sent from the control device 27A via the communication line 24a or an abnormal signal sent from the monitoring device 27B via the communication line 24b. The corresponding valve or all valves are opened or closed according to the signal. The interface 25 is a circuit that, when a single contact signal is input, converts it into an electrically isolated two contact signal and outputs it (that is, substantially the same as a one-input two-output buffer). Specifically, the water level signals 26a and 26b (26) transmitted from the external processing units 16a and 16b corresponding to the water level gauges 15a and 15b, the valves 30a, 30b, 31, 32, 33 and the like are transmitted. The coming valve opening / closing signal 28 is converted into a format suitable for the control device 27A and the monitoring device 27B, and the water surface signal 26 and the valve opening / closing signal 28 are transmitted to the control device 27A and the monitoring device 27B, respectively. The control device 27A controls the operation of the rinsing tank 1 and receives at least the water surface signal 26 and the valve opening / closing signal 28 from the contact signal interface 25, and the valves 30a, 30b, 31, 32, 33 and the like by built-in program processing. A valve control signal 29 is sent to each of these to control opening and closing. The 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 receives the liquid pressure gauge 35, the liquid flow meter 36, the gas pressure gauge 37, and Data is received from each of the gas flow meters 38, and an abnormal situation of the rinse tank 1 described later can be dealt with based on these data.
[0021]
  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 in which the wafer c cleaned with a chemical solution in the previous process is cleaned with pure water by the wafer cleaning apparatus using the rinse tank 1 will be described, but the same applies to the chemical cleaning.
[0022]
(Cleaning Control Example 1. Operation During Standby) In the above wafer cleaning apparatus, first, when the cassette 20 that has finished chemical cleaning is not scheduled to be sent to the rinsing tank 1, or when the waiting time is long. Under the control of the control device 27A, the drain automatic drain valve 31 and the normally closed automatic valve 32, the supply liquid automatic valves 30a and 30b are closed, the automatic valve 30d of the bypass pipe 21c is opened, and the needle valve 30c is opened. A small amount of pure water is supplied from the liquid introduction unit 10a to the tank cleaning unit 1A and drained from the overflow drainage unit 5 to save chemical or pure water consumption in a waiting state, that is, in an idling state. In addition, the supply liquid automatic valve 30a and the normally closed automatic valve 32 are opened in advance in accordance with the timing when the chemical liquid cleaning in the previous process is completed and the cassette 20 is sent to the rinsing tank 1. When the valve 30b, the drain automatic 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 of the punching side plate 7a, and the rinse tank 1 Is supplied to the tank cleaning section 1A, part of which flows downward as a water flow from the hole in the punching lower plate 8 through the discharge port 2 and the bypass valve 33 to the liquid discharge pipe 23, and the remaining most of the horizontal surface. It waits for the arrival of the cassette 20 in a state of being drained from the overflow drainage section 5 as a water flow.
[0023]
(Cleaning control example-2. Operation at the time of setting) When the four cassettes 20 arrive at the rinsing tank 1 and descend into the water surface for the first time toward the corresponding cradle 11, according to the control signal from the control device 27A, The gas shut-off valve 34 is opened, and a nitrogen gas having a desired flow rate is ejected from the gas ejection pipe 13 into the tank by the gas flow meter 38, and the pure water in the rinsing tank 1 is vigorously stirred and stored in each cassette 20 and it. The chemical solution adhering to the wafer c is mixed with the entire pure water in the tank, and the concentration is drastically reduced. The pure water mixed with the chemical solution is discharged from the overflow drain 5. In this way, the cleaning chemical adhering to the cassette 20 and the wafer c accommodated therein is rapidly diluted and quenched, and at the same time the rinsing effect is enhanced. This is because, particularly in the case of oxide film etching with dilute hydrofluoric acid, the dilute hydrofluoric acid adhering to the wafer is rapidly diluted and the etching action is stopped instantaneously, so that the uniformity of the oxide film etching can be improved.
[0024]
(Cleaning control example-3. Cleaning operation after setting) When four cassettes 20 are set on the cradle 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 drainage unit 5 detects the water level, the water level signal 26a output from the external processing unit 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 surface signal 26a, closes the supply liquid automatic valve 30a, opens the supply liquid automatic valve 30b and the drainage automatic valve 31, and starts from the automatic valve 30b. The supply of pure water is continued from the hole of the punching side plate 7b through the supply port 4b and the liquid introduction part 10b, but the amount of drainage discharged from the discharge port 2 exceeds that, and the water surface starts to descend. At this time, whirlpools begin to be generated in the rinsing tank 1, but immediately the water surface descends to a position where the low water surface level gauge 15b detects the water surface, and the water surface signal 26b 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 vortex flow disappears when the supply of energy is cut off. In this way, the supplied pure water causes the solution in the rinsing tank 1 to be drained so as to be pushed out from the drain port 2 in a laminar flow without being mixed, and the inside of the rinsing tank 1 is rapidly filled with pure water. 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 the drainage automatic valve 31 is opened at the same time. Again, the descent of the water surface begins. Thus, the automatic valves 30a and 30b are alternately opened and closed, the punching side plates 7a and 7b are supplied to the tank cleaning unit 1A of the rinsing tank 1, that is, pure water is alternately supplied to the left and right, and laminar drainage is performed. Each cassette 20 and the wafer c accommodated therein can be rinsed evenly and efficiently.
[0025]
(Cleaning control example-4. Operation at the final stage of washing) In the final stage of such rinsing operation, the automatic valve 30a is always opened, the automatic valve 30b and the automatic drainage valve 31 are closed, and the overflow drainage unit 5 After the pure water overflows and the floating matter floating on the water surface is washed away, each cassette 20 is taken out from the rinsing tank 1. By doing so, the cassette 20 and the wafer c that have been rinsed are eliminated from the possibility of adhering floating substances floating on the water surface when taken out from the rinse tank 1.
[0026]
(Cleaning control example-5. Operation of monitoring device) The same water level signal 26 as that 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 detects the water level. The time T1 from when the water level is detected until the low water level gauge 15b detects the water level, the time T2 from when the automatic drain valve 31 is opened until the low water level gauge 15b detects the water level, and the liquid flow meter between them 36, the integrated value V1 of the supply flow rate, the time T3 from when the low water level gauge 15b detects the water level until the automatic drain valve 31 is closed, and the high water level gauge after the automatic drain valve 31 is closed. The time T4 until 15a detects the water surface and the integrated value V2 of the supply flow rate measured by the water flow meter 24 are respectively measured and recorded in the memory of the monitoring device 27B, and are statistically processed for averaging / dispersion. From what Determining whether the original same abnormality is abnormality correction processing described below if are executed.
  Here, the occurrence of abnormality expected in the embodiment of the present invention and the response to it will be described. In this embodiment, the water is discharged 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. Therefore, the low water level gauge 15b causes malfunction or the automatic drain valve 31. When a failure that does not close occurs, the pure water surface (water level) continues to decrease, the wafer c is exposed, the attached solution evaporates, and the residue of the non-volatile components dissolved therein is deposited on the wafer surface. Pollution such as adhering as fine dust or adhering dust floating in the air. As such a failure, four causes are assumed: a first power failure, a second decrease and stop of pure water flow rate, a third water surface detection sensor malfunction, and a fourth drainage automatic valve 31 malfunction. Next, a countermeasure for preventing the wafer c from being exposed from the water surface in the embodiment for these causes will be described.
[0027]
  In the case of the first power failure, since the automatic valve 32 is a normally closed valve, it automatically closes at the time of a power failure, and drainage from the drain 2 of the rinsing tank 1 is immediately stopped, so that the water surface is lowered. There is nothing. Therefore, the wafer c is not exposed from the water surface due to a power failure. In addition, once the power supply of the valve power supply 24 is interrupted by a power failure or an emergency stop signal, even if a power failure occurs, the power supply is not automatically turned on unless the operator presses the return button. Mode "specifications (Harada Hiroyuki“ Safety Measures in Semiconductor Manufacturing ”, Safety Measures / Management Handbook in Semiconductor Manufacturing, p. 1 (1993, published by Realiz)).
[0028]
  When the second pure water flow rate drops 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, the emergency stop communication line 24b. A signal for emergency stop of the valve power supply 24 is sent from the power supply, and the power supply of the valve power supply 24 is shut off. Therefore, the normally closed automatic valve 32 is closed, the drainage from the rinse tank 1 is stopped, and the wafer c is exposed from the water surface. Is prevented.
[0029]
  A countermeasure against the third water surface sensor malfunction will be described. When the drainage flow rates from the drainage automatic 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 during which the water level drops from the high water level gauge 15a to the low water level gauge 15b is expressed by the following equation (1):
   V = (f (31) + f (33)) · Td−∫f · dt (1)
It is obtained from the relationship. Here, V is the volume of the rinsing tank 1 from the high water level gauge 15a to the low water level gauge 15b, and 積分 is the integral between 0 and Td. V, f (31), and f (33) are device constants and are known. Since f can be measured by the liquid flow meter 36, the monitoring device 27B can calculate Td using equation (1). Therefore, when the normally closed automatic valve 32 is opened and the signal indicating the water level is not transmitted from the low water level gauge 15b even after Td time after the high water level gauge 15a detects the water level, the monitoring is performed. An emergency signal is sent from the apparatus 27B to the valve power supply 24 to close all the valves 30a, 30b, 31, 32, 33 and the like, thereby preventing the wafer c from being exposed from the water surface.
[0030]
  The time Tu during which the water surface rises from the low water level gauge 15b to the high water level gauge 15a when the normally closed automatic valve 32 is closed is expressed by the following equation (2):
    V = ∫f · dt−f (33) · Tu (2)
Given in. Here, ∫ is an integral between 0 and Tu. Accordingly, when the automatic water drain valve 31 is closed and the low water level gauge 15b detects the water level and the high water level gauge 15a does not transmit the signal indicating the water level even after Tu time, the monitoring device 27B is used. Then, an emergency signal is sent to the valve power supply 24 to shut off the operation, and all the valves 30a, 30b, 31, 32, 33 and the like are closed.
[0031]
  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 it is low even after the Td and Tu times calculated by the equations (1) and (2) have elapsed. When the water level gauge 15b or the high water level gauge 15a could not detect the water level, the valve power supply 24 was immediately stopped, but instead of the low water level gauge 15b and the high water level gauge 15a from the monitoring device 27B. Control device 27AThe rinsing process can be continued by controlling the opening / closing of the automatic drain valve 31 with this signal. Moreover, 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 rinse can be continued. There is also a method in which the emergency signal is not output from the monitoring device 27B until the time obtained by adding the grace time Ty to the Td and Tu times. Either method can prevent the wafer c from being exposed from the water surface.
[0032]
  In the case of a failure where the fourth automatic drain valve 31 cannot be closed, for example, the automatic drain valve 31 is opened and the water surface descends, and the control device 27A detects the water surface after the low water level gauge 15b detects the water surface. The water level is further lowered from the low water level gauge 15b due to a time delay until the automatic drain valve 31 closes, but the water level starts to rise when the automatic drain valve 31 is closed. Again, the water surface passes through the low water level gauge 15b. First, since the time T1 from when the water surface descends to passing again through the low water level gauge 15b is substantially constant, the water level is within the time obtained by adding a margin to the T1 time after the first passage. Is not detected, the emergency signal is sent from the monitoring device 27B to the valve power supply 24 to close all the valves 30a, 30b, 31, 32, 33, etc. The automatic valve 32 can close the drainage from the drain port 2.
[0033]
(Operation of Rotation Drive Unit) Since the rotation drive unit 17 swings and rotates the wafer c in the cassette 20 up and down by the rotation of the rotary rod 19, the solution in the vertical groove 20a of the cassette 20 is replaced and the rinsing effect is improved. At the same time, the difference in the vertical rinsing effect and the etching rate is leveled, and the uniformity is improved. Further, since the solution in the rinsing tank 1 flows toward the lower drainage port 2, even if particles are generated as the rotating rod 19 rotates, the solution is quickly discharged from the drainage port 2 to contaminate the wafer c. It can be surely prevented.
[0034]
(Wafer Cleaning Apparatus Using Rinse Tanks 40A and 40B) This wafer cleaning apparatus cleans wafers c by sequentially placing them in at least the first rinse tank 40A and the adjacent second rinse tank 40B as shown on the left side of FIG. The device has the following configuration. That is, it is essential that each rinse tank 40A, 40B comprises a so-called OFR tank that supplies pure water from a supply port 41 provided at the bottom of the tank and discharges the pure water in the tank overflowing from the top of the tank. Yes. At the same time, it is essential that the two rinsing tanks 40A and 40B are arranged with a step so that the first rinsing tank 40A is lower than the second rinsing tank 40B. And in this structure, the discharge port 43 of the water collection part 42 which accommodates the pure water which overflowed from the 2nd rinse tank 40B, and the supply port 41 of the 1st rinse tank 40A are connected by the piping 44, and 2nd rinse The pure water that has overflowed into the water collecting section 42 of the tank 40B is introduced into the first rinse tank 40A due to the water level difference between the two rinse tanks 40A and 40B. For this reason, in this wafer cleaning apparatus, pure water supplied from the supply unit 41 to the second rinse tank 40B, that is, used for final cleaning, overflows from the second rinse tank 40B and is collected in the water collection unit 42. The pure water is automatically supplied to the supply port 41 of the first rinsing tank 40A through the pipe 44 and used again in the first rinsing tank 40A. Thus, in this structure, for example, the first rinse tank 40A that cleans the pure water used in the second rinse tank 40B, which is the final cleaning, and the wafer c that has been subjected to the chemical cleaning or the initial pure water cleaning. In addition, the consumption of pure water can be halved, and in addition, continuous transfer can be realized without requiring liquid transfer power such as a pump and incidental equipment.
[0035]
  In the above description of the embodiment, an example in which pure water is put in each of the rinsing tanks 1, 40 </ b> A, 40 </ b> B has been described in order, but the rinsing tank 1 may be treated with chemicals instead of pure water. There is no problem. In this case, in FIG. 4, the rinsing tank 1 is configured for chemical cleaning, and the rinsing tanks 40A and 40B are configured for pure water cleaning.
[0036]
【The invention's effect】
  As described above, by adopting each wafer cleaning apparatus of the present invention, even in a mass production line in which a total of four wafer cassettes arranged in two rows are rinsed simultaneously, cleaning rinse can be performed efficiently, and the cassette at the start of rinsing And since the chemical solution adhering to the wafer stored in it can be thinned efficiently, a uniform cleaning rinse effect is obtained, and the cleaning effect is improved, so that water saving and cleaning time of pure water are reduced, Even if a sudden power failure, water surface detection abnormality, or the like occurs, it is possible to realize excellent wafer cleaning equipment such as avoiding irreparable damage and contamination of the wafer.
[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 the rinse tank of FIG. 1;
FIG. 3 is a view showing the operation of the rotation driving means of the rinse 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 rinsing tank (1A is a tank cleaning section)
  2 is the outlet
  3a and 3b are opposite side walls of the tank
  4a and 4b are supply ports
  5 is overflow drainage
  6 and 42 are water collecting parts
  7a and 7b are punching side plates
  8 is a punching lower plate
  10a and 10b are liquid introduction parts
  13 is a gas injection pipe (gas injection means).
  15a and 15b are high and low water level gauges
  17 is a rotation driving means (19 is a rotating rod).
  20 is a cassette
  30a, 30b, 31, 32, 33 are valves (32 is a normally closed automatic valve)
  23a is a bypass tube
  25 is the interface
  27A is a control device
  27B is a monitoring device
  35 and 37 are pressure gauges
  36 and 38 are flow meters (36 is an ultrasonic flow meter)
  40A is the first rinse tank
  40B is the second rinse tank
  41 is a supply port
  42 is a water collecting section
  44 is a pipe for connection

Claims (5)

In a wafer cleaning apparatus that is used in a semiconductor manufacturing process and cleans by putting a wafer in a rinse tank having a discharge port at the bottom of the tank,
The rinsing tank is provided with a gap between the opposing side walls and a punching side plate that forms a liquid introducing portion extending vertically from the corresponding side wall to the corresponding side wall, and under each of the liquid introducing portions. A supply port that is provided on each side to connect a liquid supply pipe for cleaning liquid, and a valve that is provided in a portion of the liquid supply pipe that is close to each supply port,
Washing liquid can be alternately supplied from the liquid supply pipe to the liquid introduction parts via the valve and the supply port, and the tank is washed from the hole in the punching side plate forming the liquid introduction parts. A wafer cleaning apparatus, which is introduced into a part.  2. The wafer cleaning apparatus according to claim 1, wherein the wafer cleaning apparatus has an overflow drainage portion in which one upper end of the opposing side wall is lowered together with the discharge port.   2. The wafer cleaning apparatus according to claim 1, further comprising a normally-closed automatic valve that is provided on the discharge port side and closes when electricity is turned off.   4. The wafer cleaning apparatus according to claim 1, further comprising an ultrasonic flowmeter as means for measuring a flow rate of the cleaning liquid introduced into the liquid introducing unit and the tank cleaning unit. 5. 2. The opening and closing of a valve provided on the discharge port side and a valve provided on each of the supply ports is controlled by a water level signal when a water level or a water level in the rinse tank is detected. The wafer cleaning apparatus as described .

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