JP3133049U - Semiconductor wafer cleaning equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a cleaning treatment effect of a portion where a semiconductor wafer is contacted in a holding groove of a carrier, reduce the amount of washing water used, and process a semiconductor wafer in a short time and uniformly. A wafer cleaning apparatus is provided.
An apparatus for carrying out a cleaning process by holding a plurality of semiconductor wafers 1 on a carrier 2 and storing them in a processing tank 3 together with a cleaning liquid such as ultrapure water, for example, on the bottom side. A swinging means 5 is provided. The swinging means 5 is provided so as to swing in a direction in which the surface of the semiconductor wafer 1 tilts forward or backward, with the substantially central surface of the processing bath 3 in the direction in which the semiconductor wafers 1 are arranged in parallel as a fulcrum, and The processing tank 3 is formed so that the upper end portion of the side wall on the side perpendicular to the surface of the semiconductor wafer 1 is low at the central portion of the side wall and has a high gradient at both end portions.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor wafer cleaning apparatus capable of efficiently performing a cleaning process in a semiconductor wafer manufacturing process. More specifically, the present invention relates to a semiconductor wafer cleaning apparatus capable of efficiently cleaning a contact portion between a semiconductor wafer holding jig and a semiconductor wafer.

In the manufacturing process of a semiconductor device, for example, there are removal of SiO ₂ film with an etchant mainly composed of hydrofluoric acid, etching process mainly composed of ammonia water, etc. In addition, overflow cleaning with ultrapure water is required. The functions required for the water washing treatment of these semiconductor wafers include (1) diluting and removing the chemical solution adhering to the immediately preceding treatment process, and (2) washing the semiconductor wafer in as short a time as possible to alter the surface of the semiconductor wafer by oxidation. (3) To prevent foreign matter adhesion and back-contamination from occurring, (4) Each semiconductor wafer in a jig that accommodates a large number of semiconductor wafers is uniformly cleaned, (5) From the viewpoint of global environmental protection and effective use of water resources, it is required to perform a cleaning process with a small amount of ultrapure water as much as possible. Conventionally, an overflow type batch processing type water washing tank as shown in FIG. Is used.

  In FIG. 4, 1 is a semiconductor wafer having a diameter of about 5 inches, for example, and 2 is a jig for holding a large number of semiconductor wafers 1 and is hereinafter referred to as a carrier. In the carrier 2, the side plates 21 are arranged at regular intervals, and the semiconductor wafer 1 is held in the holding grooves 22. For example, about 25 to 50 semiconductor wafers 1 are held on a carrier 2. A through hole 23 is formed on the bottom surface of the carrier 2 so that the cleaning ultrapure water 4 flows. The ultrapure water 4 introduced from the water conduit 31 flows into the carrier 2 side uniformly from the perforated portions 34 of the punching plate 33 through the preliminary chamber 32. The introduced ultrapure water 4 passes through the semiconductor wafer 1 and the carrier 2 and overflows from the upper end of the side wall of the processing tank 3 (indicated by A in FIG. 4). In this case, the punching plate 33 is kept horizontal and the semiconductor wafer 1 is held vertically (the surface of the semiconductor wafer 1 is made perpendicular to the punching plate 33), and the introduced ultrapure water 4 is introduced through the perforated portion 34. Cleaning the semiconductor wafer 1 so as to have a laminar flow is important from the viewpoint of flowing out the particles separated by the cleaning without reattachment.

  In order to determine whether or not the semiconductor wafer 1 has been completely cleaned, the etching solution used in the previous process is usually an electrolyte. Therefore, when the electrolyte is mixed in ultrapure water, the specific resistance of the cleaning water is determined. This can be determined by measuring the specific resistance of the wash water that overflows and flows out. For example, FIG. 3 shows the change in the specific resistance value of the cleaning water when the water flow rate is set to 9 liters / minute and the carrier 2 is intentionally vibrated in the treatment tank 3 after performing normal water washing for 10 minutes. As Q. That is, when water washing is performed, the specific resistance value recovers exponentially in proportion to the water flow time, and close to the specific resistance value of the raw water (ultra pure water) after washing for about 10 minutes. Thus, if the specific resistance of the cleaning water becomes approximately the same as the specific resistance of ultrapure water, it can be considered that the chemical components such as the etching solution adhering to the semiconductor wafer 1 are almost removed.

However, if the carrier 2 is intentionally vibrated when the elapsed time is 10 minutes, for example, the specific resistance value may rapidly decrease at that point as shown by Q in FIG. This indicates that the semiconductor wafer 1 is not sufficiently cleaned. In order to prevent this, it is necessary to pass a large amount of water or reduce the number of processed semiconductor wafers 1. Therefore, when the apparatus shown in FIG. 4 (contains 25 to 50 semiconductor wafers 1 having a diameter of 5 inches), a water flow rate of 15 liters / minute or more and a water washing time of 15 minutes or more are required.

  As an attempt to improve the manifestation of the lack of water washing by applying vibration to the semiconductor wafer 1 as described above, a rotating roller is brought into contact with one end of the semiconductor wafer 1 during water washing to force the semiconductor wafer 1. It is known to provide means for preventing the semiconductor wafer 1 from sticking to the holding groove 22 by rotating the semiconductor wafer 1. As another means, a method of attaching a handle to the carrier 2 and swinging the carrier 2 through the handle is also known. However, in the former method, particles are generated at the sliding portion of the rotating body, and in the latter method, there is a problem that the chemical solution remains in the gap between the contact portion between the carrier 2 and the handle, which is in terms of reliability. There were difficulties.

Furthermore, because of the inclination of the processing tank 3 and the like, the cleaning water flows out from only a part of the processing tank 3, and dust accumulates at the four corners of the upper end of the side wall of the processing tank 3, thereby fulfilling the original function of overflow. For the purpose of improving the elimination, there is also known a method of providing a motor 7 or the like on the bottom surface of the processing tank 3 and swinging like a seesaw with its center as a fulcrum as shown in FIG. Reference 1). In FIG. 5, 8 is an outer box, and the same parts as those in FIG.
Japanese Utility Model Publication No. 1-173334

  As described above, when cleaning is performed by holding a semiconductor wafer in a carrier and introducing ultrapure water or the like from the bottom side to overflow from the upper end of the side wall, the semiconductor wafer is in contact with the side plate of the carrier. Since the part cannot be cleaned sufficiently, it is necessary to increase the amount of water and increase the cleaning time in order to perform sufficient cleaning. However, water resources are wasted and semiconductor device costs are increased. There is a problem of causing. In particular, when manufacturing a complicated semiconductor device such as an integrated circuit (IC), generally, a washing process of about 20 times is required to complete the manufacturing process, and the price of ultrapure water is equal to that of general tap water. Since it is several hundred times larger than that, the amount of ultrapure water consumed and the cost of wastewater treatment are enormous. Therefore, in the manufacturing process of semiconductor devices such as ICs, how to reduce the amount of ultrapure water used is an important theme, and it is desirable to suppress consumption of water resources from the viewpoint of global environmental conservation. . In addition, even if the amount of water and the time are sufficiently increased as described above, a stain defect or the like due to residual chemicals may frequently occur in the holding groove portion of the carrier. In particular, the larger the diameter of the wafer, the smaller the inclination of the semiconductor wafer in the carrier and the more the weight increases. Therefore, the fluctuation of the semiconductor wafer in the liquid is less likely to occur, and there is a tendency for defective stains to occur frequently. In order to completely solve such a problem, it is necessary to go to single wafer processing for processing semiconductor wafers one by one, but productivity is significantly lower than batch processing for processing many wafers at once. There is a problem of increased costs.

  On the other hand, from the viewpoint of increasing productivity, the number of holding grooves in the carrier is increased, that is, the pitch of the holding grooves is reduced to increase the number of semiconductor wafers held in the same size carrier, Although it is required to carry out means such as increasing the diameter, shortening the washing time, reducing the amount of water flow, alone or in combination of two or more, such a request is made in the short time mentioned above. Contrary to thorough cleaning with less water.

Furthermore, in order to ensure cleaning as described above, if a large amount of ultrapure water is introduced, the semiconductor wafer can be forcibly shaken in the carrier by water flow or water pressure, which is uneconomical. In addition, there is no guarantee that the entire amount of the semiconductor wafer accommodated in the carrier fluctuates away from the inner wall of the holding groove. Therefore, there is a problem that even if ultrapure water is introduced in a large amount, cleaning for a long time must be performed. In addition, when a large amount of ultrapure water is introduced, the water flow is disturbed in the treatment tank to become a so-called turbulent flow, and even if it is suitable for removing the etching solution or the like, the semiconductor wafer is subjected to particle contamination by dust generation.

  Furthermore, when the swinging means as shown in FIG. 5 is provided, the cleaning water in the treatment tank flows out from the tilted low side at a time when tilted to one side, and this time, the tilt is reversed. Since a large amount of cleaning water flows out from the side at once, turbulent flow occurs in the cleaning water in the processing tank, and the particles separated from the semiconductor wafer as described above are stirred in the processing tank and returned to the lower side. The problem of contamination of redeposition occurs and eventually cleaning for a long time is required. Moreover, as shown in FIG. 5, even if the semiconductor wafer is swung in a direction parallel to the surface of the semiconductor wafer, the contact portion between the semiconductor wafer and the carrier is hardly affected, and the contact portion between the semiconductor wafer and the carrier described above. It does not contribute at all to measures for insufficient cleaning.

  The present invention has been made to solve such problems, and enhances the cleaning effect of the portion where the semiconductor wafer is in contact with the holding groove of the carrier, reduces the amount of cleaning water used, and in a short time. In addition, an object of the present invention is to provide a semiconductor wafer cleaning apparatus capable of uniformly processing a semiconductor wafer.

  The present inventor conducted intensive studies to solve the above-mentioned problems, and first followed the cleaning process of the semiconductor wafer accommodated in the carrier. That is, only one semiconductor wafer was held on the carrier, and a water flow amount (specifically, 5 liters / minute) was ensured so that the semiconductor wafer was surely shaken during the water washing, and the carrier was washed with water for 10 minutes. Immediately after that, the specific resistance value of the overflow water was measured by intentionally vibrating the carrier. As a result, the specific resistance value did not decrease at all. In this way, if the number of semiconductor wafers 1 held in the carrier is gradually increased and all the semiconductor wafers are swung, a deliberate vibration is given after the washing time when the specific resistance value of the raw water is almost close. However, it was confirmed that there was no decrease in the specific resistance value of the overflow water. Even if only the carrier is swung in the tank, or even if the entire processing tank is swung in a general processing tank in which the upper end and the lower end of the side wall are parallel, the turbulent flow of cleaning water in the tank It is found that particle contamination is caused on the contrary, and the processing tank is seesawed (swinged) in the direction perpendicular to the surface of the semiconductor wafer, and the upper end of the side wall of the processing tank is aligned with the swinging direction. Since the washing water is not drained all at once even if it swings, and turbulent flow does not occur inside, it can be completely washed in a short time with a small amount of ultrapure water. I found that I can do it.

  A semiconductor wafer processing apparatus according to the present invention is provided with a jig for holding a plurality of semiconductor wafers together with a processing tank having an open top surface for containing cleaning water, and a bottom surface side of the processing tank. Swinging means for moving the swinging means, wherein the swinging means is provided so as to swing in a direction in which the surface of the semiconductor wafer accommodated in the processing bath is tilted forward or backward, and the processing bath Is the maximum value of the angle at which the upper end of the side wall perpendicular to the surface of the semiconductor wafer has a low gradient at the center of the side wall and a high gradient at both ends, and the angle of the gradient causes the processing bath to swing. It is characterized by being formed at substantially the same angle as.

  Here, “gradient” means that there is a difference in height between the lowest point and the highest point, and includes not only a continuous inclined surface but also a height due to a stepped step.

According to the present invention, since the processing tank containing the semiconductor wafer is swung in the direction perpendicular to the surface of the semiconductor wafer, the semiconductor wafer held in the holding groove of the jig (carrier), the side plate of the carrier, Since the contact is alternately performed on the front and back of the semiconductor wafer and the contact at the same place does not continue, the cleaning process can be surely performed. That is, the lower end portion of the semiconductor wafer is supported by the bottom surface in the holding groove of the carrier, and the upper end portion is held against one of a pair of opposing side plates forming the holding groove. Therefore, when the processing tank is tilted to one side by swinging, the carrier for holding the semiconductor wafer is also tilted, and the upper end portion of the semiconductor wafer is tilted and held on the tilted lower side plate side. One side of the pair of side plates becomes lower as the processing tank swings, so that the held side plates change alternately as the semiconductor wafer swings. As a result, the contact portion with the side plate can be completely cleaned.

  On the other hand, of the upper end portion of the side wall of the processing tank, the upper end portion of the side wall perpendicular to the surface of the semiconductor wafer is formed so as to have a low gradient at the center portion of the side wall and a high gradient at both end portions (become inclined surfaces). By aligning the inclination angle with the maximum angle of oscillation, the upper end of the inclined side wall of the processing tank that is lowered by the inclination becomes the horizontal plane when the angle is the most inclined by the oscillation. However, the washing water flows out due to overflow, but it does not happen that a large amount of washing water overflows at a time due to the inclination. That is, since the side wall of the processing tank is formed higher on the end side than the center part in accordance with the swinging direction, when the processing tank is tilted, the processing liquid moves to the lower side, but the swinging itself is gently By doing so, the processing liquid also moves to the lower side without overflowing, so that it does not overflow all at once, and only the overflowing processing liquid is discharged from the upper end of the side wall where the inclined surface is formed. Therefore, a turbulent flow is generated in the processing liquid, and particles separated from the semiconductor wafer do not adhere to another part of the semiconductor wafer or another semiconductor wafer at all.

  As a result, even when cleaning is performed with cleaning water such as ultrapure water or pure water, it is possible to completely clean with a small flow rate (water flow rate) of cleaning water in a short cleaning time.

  Next, a semiconductor wafer cleaning apparatus according to the present invention will be described with reference to the drawings. The semiconductor wafer cleaning apparatus according to the present invention has a structure as shown in FIG. In other words, this processing is performed by a device that holds a plurality of semiconductor wafers 1 with a jig (carrier 2) and stores the semiconductor wafers 1 together with cleaning water such as ultrapure water in the processing tank 3 to perform this processing. A swinging means 5 for swinging the processing tank 3 is provided on the bottom side of the tank 3. In the present invention, the oscillating means 5 has a substantially center plane (a plane perpendicular to the paper at the center in the x direction) as a fulcrum in a direction perpendicular to the surface of the semiconductor wafer 1 (x direction in FIG. 1). , And the processing tank 3 is configured such that the upper end of the side wall perpendicular to the surface of the semiconductor wafer 1 is low at the position of the center plane and has a high gradient (difference in height) at both ends. ).

  The semiconductor wafer 1 is generally a wafer in a manufacturing process for manufacturing a semiconductor device, and the carrier 2 is formed with a holding groove 22 so that the semiconductor wafer 1 can be held one by one, The side plate 21 forming the holding groove 22 is continuously arranged side by side. A through hole 23 is formed on the bottom surface of the holding groove 22 so that cleaning water such as ultrapure water 4 is introduced into the holding groove 22 from below to overflow from above.

The processing tank 3 is provided with a water guide pipe 31 on the bottom surface, and a punching plate 33 having a perforated portion 34 formed as an inner bottom is attached to the punching plate 33. 2 is fixed by a fixture 35. A hose 39 is connected to the water conduit 31, for example, cleaning water such as ultrapure water 4 is introduced, and a through hole 23 formed in the bottom surface of the carrier 2 from the perforated portion 34 of the punching plate 33 through the preliminary chamber 32. Then, the periphery of the semiconductor wafer 1 is raised. In the present invention, of the side walls of the processing tank 3, the upper end of the side wall 36 of the surface perpendicular to the surface of the semiconductor wafer 1 (surface parallel to the paper surface) is low at the center and high at both ends. It has an inclined surface. The inclination angle θ2 of the slope B with respect to the bottom surface (x-axis) is formed to be approximately the same as the swing angle θ1 that is the maximum angle for swinging the processing tank 3 described later. By setting the inclination angle to such an angle, the upper end portion of the treatment tank 3 becomes a horizontal plane in the state of being most inclined by the swing, and the washing water overflows from the highest end portion side of the inclined plane. Therefore, the washing water does not stay. The inclined surface of the upper end portion of the side wall 36 may be inclined stepwise instead of a continuous inclined surface.

  Further, in the present invention, slits 37 are formed on the inclined surface at regular intervals, and the overflowing cleaning liquid is allowed to flow out from the slits 37 so that the cleaning water flows out in a clean laminar flow without unnecessary stirring in the tank. Has been.

  A swinging means 5 is provided on the bottom surface of the processing tank 3 so that the processing tank 3 can be swung. In the example shown in FIG. 1, the swinging means 5 is configured to support both ends in the x direction on the bottom surface of the processing tank 3 with a jig cylinder 52, a piston 53, and a roller 54 provided on the fixed plate 51. The seesaw motion can be made by performing the up and down movement of 53 in the opposite direction. The piston 53 is moved up and down by adjusting the air pressure via the air tube 55. Although not shown, by attaching a speed controller to the air tube 55, it is possible to easily control the air pressure and finely adjust the swing. Further, the swinging means 5 is not limited to an example in which the piston is controlled by air pressure. For example, the swinging means 5 is supported by the center portion of the bottom surface of the carrier 2 as a fulcrum and sprays ultrapure water alternately on both sides thereof. In addition, it is possible to make a seesaw motion by air pressure.

  The maximum inclination angle θ1 of the rocking by the seesaw motion is set to be 3 to 6 °, for example. The reason why the processing tank 3 is swung is that the inclination due to the swinging as shown in FIG. 2 is an enlarged cross-sectional explanatory diagram of the state in which the semiconductor wafer 1 is held in the holding groove 22 (the dimensional relationship is not accurate). This is because the tilt direction is changed so that the upper portion of the semiconductor wafer 1 is tilted to the left or tilted to the right, and the semiconductor wafer 1 may be swung within an angle range that can change the tilt of the semiconductor wafer 1. That is, since the semiconductor wafer 1 is only placed on the bottom surface of the holding groove 22, for example, when the bottom surface is tilted to the left side in the figure, the side plate 21a becomes lower than the side plate 21b, and the upper portion of the semiconductor wafer 1 is It falls to the lower side plate 21a by its own weight and is held by the side plate 21a. Further, when tilted to the right side, the side plate 21b becomes lower, and the upper portion of the semiconductor wafer 1 is tilted and held on the lower side plate 21b side. In FIG. 1, the angle between the horizontal plane H and the bottom surface of the processing tank 3 when the inclination of the processing tank 3 is maximum, that is, the x direction is indicated by θ1. In the case of tilting to the opposite side, the right cylinder 53 in the figure is lowered and the left cylinder 53 is lifted and tilted in the opposite direction. In this case, the maximum tilt angle with respect to the horizontal plane H is −θ1.

  Next, the operation of this cleaning processing apparatus will be described. The semiconductor wafer 1 to be cleaned is held in the holding groove 22 of the carrier 2, and is fixed to the punching plate 33 in the processing tank 3 with a fixing tool 35. The position of the processing tank 3 in the initial state is not limited, but the carrier 2 can be easily fixed if it is set to a horizontal position by adjusting the swinging means 5. Then, the ultrapure water 4 is introduced into the treatment tank 3 through the hose 39 at a rate of 5 liters / minute, for example. The introduced ultrapure water 4 initially accumulates in the spare chamber 32. When the spare chamber 32 is full, the ultrapure water 4 proceeds from the perforated portion 34 of the punching plate 33 toward the carrier 2 and passes through the bottom surface of the carrier 2. From 22, the semiconductor wafer 1 in the holding groove is washed upward. The introduced ultrapure water 4 proceeds upward while filling the outside of the carrier 2. When the ultrapure water 4 is almost filled in the treatment tank 3, the swinging means 5 is operated to swing left and right.

The oscillating means 5 adjusts the air pressure in the air tube 55 so that the maximum inclination angle becomes 3 to 6 ° in about 5 seconds from the horizontal state of the processing tank 3, for example, so that one cycle is 20 seconds. A degree of swinging motion can be performed. If this oscillation cycle is too early, turbulent flow is generated in the cleaning liquid, which is not preferable, and if it is too late, cleaning in a short time cannot be performed. The air pressure can be freely adjusted by a speed controller (not shown) and can be swung at a desired cycle.

  By this method, the semiconductor wafer 1 having a 5 inch diameter is accommodated in the carrier 2 and cleaned by introducing the ultrapure water 4 at a rate of 5 liters / minute as described above. The change in the specific resistance of the overflowing wash water was measured by intentionally applying vibration to the water. The result is indicated by P in FIG. FIG. 3 shows the change in specific resistance when the water flow rate is 9 liters / minute in the same manner in the conventional non-oscillating state as Q. As is clear from FIG. According to the device, it can be seen that even if the treatment tank is intentionally vibrated on the way, the specific resistance does not rapidly change and is completely cleaned. On the other hand, when the conventional cleaning apparatus is not used to swing, as described above, the vibration of the ultrapure water 4 is vibrated from the outside even though the flow rate of the ultrapure water 4 is almost double. When applied to the treatment tank 3, the specific resistance suddenly decreased, indicating that it was not completely cleaned, and cleaning for 15 minutes or more was required for complete cleaning.

  As described above, according to the present invention, the amount of ultrapure water used is significantly reduced to the conventional 5/9 (flow rate per unit time) × 10/15 (hours) = 37%, and cleaning is not possible. Sufficient things do not occur at all, and furthermore, there is no stain defect such as chemical residue remaining in the part located in the holding groove, etc., and very reliable cleaning treatment can be performed .

  The above explanation is an example of cleaning a semiconductor wafer with ultrapure water. However, not only cleaning with ultrapure water, but also cleaning with pure water, normal tap water, etc., saves cleaning water as well. In addition, the reliability of cleaning can be greatly improved.

It is a section explanatory view showing one embodiment of a processing device of a semiconductor wafer by the present invention. It is a figure which shows typically a mode that the semiconductor wafer hold | maintained in the holding groove | channel of the carrier of FIG. 1 changes with rocking | fluctuation of a processing tank. It is a figure which shows the change of the specific resistance (cleaning degree) at the time of wash | cleaning a semiconductor wafer using the processing apparatus shown in FIG. 1 compared with the conventional case. It is sectional explanatory drawing which shows the outline | summary of the washing | cleaning processing apparatus of the conventional semiconductor wafer. It is a figure which shows the other example of the washing | cleaning processing apparatus of the conventional semiconductor wafer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Carrier 3 Processing tank 4 Ultrapure water 5 Swing means
21 Side plate
22 Holding groove
23 Through hole
31 Water conduit
32 Spare room
33 Punching plate
34 Perforated part
35 Fixture
36 Side wall of the processing tank on the side perpendicular to the surface of the semiconductor wafer
37 Slit
38 Side wall of the processing tank on the side parallel to the surface of the semiconductor wafer
39 hose
51 Fixed plate
52 Jig cylinder
53 Piston
54 Laura
55 Air tube

Claims (1)

  A processing tank having an open top surface for storing cleaning water together with a jig for holding a plurality of semiconductor wafers; and a swinging means provided on the bottom surface side of the processing tank for swinging the processing tank. The swinging means is provided so as to swing in a direction in which the surface of the semiconductor wafer accommodated in the processing bath is tilted forward or backward, and the processing bath is perpendicular to the surface of the semiconductor wafer. The side wall upper end of the side wall is low at the center of the side wall and has a high gradient at both end sides, and the angle of the gradient is formed to be substantially equal to the maximum value of the angle at which the processing tank is swung. A semiconductor wafer cleaning apparatus.

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