JP3691227B2 - Liquid processing method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid processing method and apparatus for performing chemical processing, cleaning processing and drying processing while rotating an object to be cleaned such as a semiconductor wafer.
[0002]
[Prior art]
In general, in a semiconductor device manufacturing process, for example, a natural oxide film formed by contact with particles or the atmosphere attached to the surface of an object to be processed such as a semiconductor wafer (hereinafter referred to as a wafer) or a liquid crystal display (LCD) substrate is used. A cleaning process is performed for removal. As one of methods for cleaning an object to be processed, a single wafer cleaning method using a spin-type apparatus is generally known.
[0003]
In the spin-type cleaning method, a chemical solution such as a hydrofluoric acid solution is supplied to the surface of the object to be processed while the object to be processed is held and rotated by a spin chuck that is a rotation holding means, and then cleaning water such as pure water is supplied. After being supplied, spin drying is performed. And in the process of drying a to-be-processed object, in addition to blowing off pure water by spin, drying is also promoted by spraying an inert gas, for example, nitrogen (N2) gas, on the surface of a to-be-processed object ( JP-A-7-37855). In the technique described in Japanese Patent Laid-Open No. 7-37855, after a wafer as an object to be processed is cleaned with a cleaning liquid, the wafer is rotated to sufficiently reduce the cleaning liquid on the wafer surface, and then N2 is placed at the center of the wafer surface. It is a technology that performs drying by jetting gas.
[0004]
[Problems to be solved by the invention]
By the way, as an indicator of the drying performance of an object to be processed, it is possible to mention how much “water marks” due to poor drying, usually called watermarks, are generated. Was inevitable. As shown in FIG. 14, when a surface of an object to be processed, for example, a wafer W is treated with hydrofluoric acid, first, as shown in FIG. 14A, the nozzle 2 is held while rotating the wafer W while being held by the spin chuck 1. Then, the hydrofluoric acid solution A is supplied to the surface of the wafer W, and then, as shown in FIG. 14B, pure water B is supplied from the nozzle 3 to rinse the surface, and the pure water B is blown off by centrifugal force. A part of the pure water B at this time remains on the surface of the wafer W as shown in FIG. 14C and remains as the watermark 4 as shown in FIG.
[0005]
As described above, the cause of the water mark 4 is that when the water dries, it finally becomes spherical, and this remains on the surface of the wafer W due to surface tension, and the water, oxygen in the air, the surface of the wafer W It reacts with silicon to produce H2SiO3, and this reaction product precipitates, or a very small amount of silica (SiO2) contained in pure water precipitates to form a water mark.
[0006]
In particular, in the case of hydrofluoric acid treatment, since SiO2 on the surface of the wafer W is removed and Si is exposed, a reaction is likely to occur. Further, as shown in FIGS. 15A and 15B, when the surface of the wafer W is a hydrophobic film such as polysilicon and has the recess 5, the water tends to remain in a spherical shape and the water does not easily fly. It becomes easier to remain as a watermark.
[0007]
In the method of supplying N2 gas to the center of the wafer W during the drying process, that is, the remaining water can be reduced by the N2 gas. However, as described above, the surface of the wafer W is hydrophobic such as polysilicon. Since there is a recess 5 in the film, the current situation is that the watermark has not been completely removed.
[0008]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a liquid processing method and apparatus capable of reducing particle contamination by chemical treatment of the surface of an object to be processed, then cleaning, and drying to reduce particle contamination. It is what.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 Placed in the cup A process of supplying a cleaning liquid to the surface of the object to be processed while rotating the object to be processed held by the rotation holding means, and a step from the center of the surface of the object to be processed toward the outer periphery while rotating the object to be processed. Supplying an inert gas cooled and dried, and scanning the inert gas supply means And supply of inert gas Is stopped at a position before the outer peripheral end face of the workpiece. And then stop the rotation of the workpiece (Claim 1).
[0010]
The invention according to claim 7 Arranged in the cup, A rotatable rotation holding means for holding the object to be processed; a cleaning liquid supplying means for supplying a cleaning liquid to the surface of the object to be processed; an inert gas supplying means for supplying an inert gas to the surface of the object to be processed; A moving mechanism that scans and moves the inert gas supply means from the center of the object to be processed toward the outer periphery; a cooling means that cools the temperature of the inert gas supplied to the object to be processed; and rotation of the rotation holding means And scanning movement of the inert gas supply means With inert gas supply And a control unit for controlling the inert gas supply unit based on a signal from the control unit. And supply of inert gas Is stopped at a position before the outer peripheral end surface of the workpiece. Then, stop the rotation of the workpiece It is formed as follows.
[0011]
In the present invention, when supplying the inert gas, it is preferable to scan the inert gas supply means while accelerating the rotation of the object to be processed, so that the inert gas supply means does not move to the surface of the object to be processed. It is better to supply the active gas (claim 2). At this time, in the case of the liquid processing method according to claim 2, the rotational speed of the object to be processed and the temporal relationship between the start and end of the scanning movement of the inert gas supply means are arbitrary as long as the drying efficiency is not significantly reduced. However, preferably, the object to be processed is Start supplying inert gas just before rotational acceleration, It is preferable that the start of the rotation acceleration and the start of the scan movement of the inert gas supply means are substantially simultaneous, and the rotation acceleration of the object to be processed is terminated during the scan movement of the inert gas supply means. (Claim 3). In addition, the object to be processed Start supplying inert gas just before rotational acceleration, The start of the rotation acceleration and the start of the scan movement of the inert gas supply means are substantially simultaneous, and after the rotation acceleration of the object to be processed is finished, this is not effective when the object to be processed is rotated at a constant speed. It is preferable to end the scanning movement of the active gas supply means.
[0012]
In addition, when supplying the inert gas, the inert gas supply means tilts the gas outlet of the object to be processed and supplies the inert gas in the direction in which the inert gas supply means tries to scan. The inert gas supply means may be moved while scanning ( Claim 5 or claim 8 ). In this case, it is preferable that the inert gas supply means is gradually inclined from the vertical state in the vicinity of the center of the object to be processed, and is scanned after the predetermined angle is reached ( Claim 6 or Claim 9 ).
[0013]
Claims 1, 7 According to the described invention, the cleaning liquid is supplied to the surface of the object to be processed while rotating the object to be processed, and then the liquid cooled from the center of the surface of the object to be processed toward the outer periphery while rotating the object to be processed. Since the cleaning gas remaining on the surface of the object to be processed is removed by supplying the active gas, the speed of the chemical reaction that causes the watermark can be reduced, and the generation of the watermark can be surely reduced. .
[0014]
Also, The cleaning liquid is supplied to the surface of the object to be processed while rotating the object to be processed, and then the inert gas is supplied from the center of the object to be processed toward the outer periphery while rotating the object to be processed. In addition to actively removing the cleaning liquid remaining on the substrate, it can be dried, and by stopping at a position in front of the outer peripheral end surface of the object to be processed, an inert gas is sprayed around the object to be processed. This eliminates the possibility of rolling up particles.
[0015]
Further, the drying time can be shortened by scanning the inert gas supply means while accelerating the rotation of the object to be processed, and supplying the inert gas from the inert gas supply means to the surface of the object to be processed. At the same time, the drying efficiency can be improved ( Claims 2, 3, and 4 ).
[0016]
In addition, the inert gas supply means is scanned and moved while the inert gas supply means is inclined to the surface of the object to be processed and the inert gas supply means supplies the inert gas in the direction of scanning movement. By doing so, since the inclined inert gas holding means can more effectively remove the cleaning liquid on the surface of the object to be processed, the generation of watermarks and the generation of particles can be further reduced ( Claims 5 and 8 ). In this case, the inert gas supply means is gradually moved from the vertical state in the vicinity of the center of the object to be processed, and the inert gas supply means is easily positioned by moving the scan after the predetermined angle is reached. be able to( Claims 6, 9 ).
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings. In this embodiment, a case where the liquid processing apparatus according to the present invention is applied to a semiconductor wafer cleaning processing apparatus will be described.
[0018]
◎ First embodiment
FIG. 1 is a cross-sectional view showing the main part of the cleaning apparatus to which the first embodiment of the liquid processing apparatus according to the present invention is applied, and FIG. 2 is a schematic plan view thereof. The cleaning apparatus includes a rotation holding means, for example, a spin chuck 10 that holds a wafer W as an object to be processed and rotates on a horizontal plane, a cup 20 that surrounds the outer periphery and the lower side of the spin chuck 10 and the wafer W, and the wafer W. A chemical solution supply nozzle 31 which is a chemical solution supply means for supplying a chemical solution such as a hydrofluoric acid solution to the surface of the wafer, a pure water supply nozzle 32 which is a cleaning solution supply means for supplying a cleaning solution such as pure water to the surface of the wafer W, and the surface of the wafer W. And an N2 gas supply nozzle 33 which is an inert gas supply means for supplying an inert gas such as nitrogen (N2) gas, and a moving mechanism 34 for moving the N2 gas supply nozzle 33 from the center of the wafer W toward the outer periphery. are doing. Further, the cleaning device includes a control unit 40 for controlling the supply of the chemical solution (hydrofluoric acid solution), pure water and N2 gas from the chemical solution supply nozzle 31, the pure water supply nozzle 32, and the N2 gas supply nozzle 33. (See FIG. 3).
[0019]
The spin chuck 10 is mounted on a mounting plate 13 mounted on an upper portion of a rotating shaft 12 that rotates about a vertical axis by a motor 11, and is provided around a peripheral portion of the mounting plate 13, and a wafer W is mounted on the mounting plate 13. 13 and a fixed holding unit 14 that holds the peripheral edge of the wafer W in a state where it floats. In this case, as shown in FIG. 2, the fixed holding unit 14 is partially cut away in the circumferential direction so that the wafer W can be transferred to and from a transfer means (not shown). Further, in order to hold the wafer W, in addition to the fixed holding part 14, the swinging holding part 15 or a combination thereof may be used.
[0020]
4 and 5 are enlarged views of the spin chuck 10 when the fixed holding unit 14 and the swinging holding unit 15 are used in combination. Oscillating holding parts 15 are provided on both sides so as to sandwich fixed holding parts 14 provided at a plurality of positions (three cases are shown in FIG. 4) on the peripheral edge of the mounting plate 13. As shown in FIG. 5, the swingable holding portion 15 is formed to be swingable with a horizontal support shaft 15d as a fulcrum, and a lower end portion 15a below the horizontal support shaft 15d is connected to the horizontal support shaft 15d. It is formed so as to be longer than the upper upper end 15b. Further, the upper end portion 15b is provided with an abutting portion 15c that contacts and holds the wafer W. In the oscillating holding portion 15 configured as described above, when the spin chuck 10 rotates, the lower end portion 15a is inclined outward by the action of centrifugal force, and the upper end portion 15b is supported by the horizontal support shaft 15d as a fulcrum. Tilt toward the center. Therefore, the contact portion 15c can be held so as to press the wafer W.
[0021]
The cup 20 is configured in a double cup structure including an inner cup 21 and an outer cup 22, and is configured to be lifted and lowered by a lifting means 23. In this case, the inner cup 21 and the outer cup 22 receive and discharge liquid splashed when the wafer W rotates, and the receiving port 22a of the outer cup 22 is positioned above the receiving port 21a of the inner cup 21. It is formed to do.
[0022]
The inner cup 21 and the outer cup 22 are configured so that the atmosphere in the cup is exhausted by a common exhaust passage 24 on the lower side, and drain pipes are respectively provided at the bottoms of the inner cup 21 and the outer cup 22. 25 and 26 are provided. Further, a receiving cup 27 is provided so as to surround the inside of the inner cup 21, that is, the lower region of the spin chuck 10, and the liquid accumulated in the receiving cup 27 is discharged through the drain pipe 25. It is like that. Thus, by making the cup 20 into an inner and outer double structure, the chemical solution (hydrofluoric acid solution) and the cleaning solution (pure water) can be discharged and collected separately.
[0023]
The chemical solution supply nozzle 31 and the pure water supply nozzle 32 are fixed by support members 37 and 38 extending horizontally from upper portions of rotary shafts 35 and 36 provided vertically on the outside of the cup 20, respectively. The rotation shafts 35 and 36 are rotated about the vertical axis by the rotation mechanisms 41 and 42, respectively, and the nozzles 31 and 32 are positioned more than the outer cup 22 and the supply position where the front end faces the central portion of the wafer W. It is comprised so that it may rotate between outer standby positions.
[0024]
Further, as shown in FIG. 3, the chemical solution supply nozzle 31 and the pure water supply nozzle 32 are connected to a hydrofluoric acid solution supply source 46 and a pure water supply source 47, which are chemical solution supply sources, through valves 43 and 44, respectively. A hydrofluoric acid solution or pure water, which is a chemical solution, is supplied to the chemical solution supply nozzle 31 and the pure water supply nozzle 32 by a supply means such as a pump (not shown) so as to be supplied to the wafer W.
[0025]
On the other hand, the N2 gas supply nozzle 33 can reciprocate between a supply start position near the center of the wafer W and a standby position outside the outer cup 22 by a moving mechanism 34 disposed outside the cup 20. It is comprised so that it can move toward the outer periphery from the center of the wafer W. In this case, the moving mechanism 34 is composed of an air cylinder 34a arranged in a horizontal state, and the support member 34d extending horizontally from the mounting member 34c attached to the piston rod 34b of the air cylinder 34a is connected to the support member 34d. An N2 gas supply nozzle 33 is fixed. The moving mechanism 34 is not necessarily a cylinder, and may be a linear driving mechanism such as a belt drive or a ball screw, or may be a moving mechanism for the chemical solution supply nozzle 31 and the pure water supply nozzle 32. Such a rotational drive mechanism may be used.
[0026]
Further, as shown in FIG. 3, the N2 gas supply nozzle 33 is connected to an N2 gas supply source 48 via a valve 45, and N2 gas is supplied to the N2 gas supply nozzle 33 by a supply means such as a compressor (not shown). It is configured to be supplied and supplied (jetted) toward the wafer W. In this case, an N2 gas cooling means (not shown) is provided between the N2 gas supply source 48 and the N2 gas supply nozzle 33 so that the temperature of the injected N2 gas is a low temperature of 2 to 10 [deg.] C., for example. You may do it. By cooling the temperature of the N2 gas in this way, the rate of the chemical reaction for generating H2SiO3 that causes water marks from the Si on the surface of the wafer W, oxygen in the air, and water can be reduced. Therefore, the generation of watermarks can be reduced more reliably.
[0027]
The control unit 40 that controls the supply of the chemical solution (hydrofluoric acid solution), pure water, and N2 gas from the chemical solution supply nozzle 31, the pure water supply nozzle 32, and the N2 gas supply nozzle 33 follows a program stored in advance in the memory unit. The rotation mechanisms 41 and 42 and the moving mechanism 34 of the nozzles 31, 32 and 33 are controlled, and the valves 43, 44 and 45 can be controlled.
[0028]
Next, the cleaning method performed using the said cleaning apparatus is demonstrated. First, the wafer W is placed and held on the placement plate 13 of the spin chuck 10. Next, when the motor 11 is driven, the spin chuck 10 is rotated at a rotational speed of, for example, 300 rpm, and the chemical solution supply nozzle 31 is rotated from the standby position to the supply position, that is, the position where the tip is opposed to the central portion of the wafer W. As shown in FIG. 6A, 0.5% hydrofluoric acid solution A, for example, is supplied from the chemical solution supply nozzle 31 to the vicinity of the center of the surface of the wafer W at a flow rate of, for example, 1000 ml / min. The natural oxide film on the surface of the wafer W is removed. At this time, the cup 20 rises so that the receiving port 21a of the inner cup 21 faces the peripheral edge of the wafer W, and the inside of the exhaust path 24 is exhausted by an exhaust means (not shown), whereby the surface of the wafer W The hydrofluoric acid solution splashed from is sucked into the inner cup 21 through the receiving port 21 a and is collected through the drain pipe 25.
[0029]
After the natural oxide film on the surface of the wafer W is removed as described above, the chemical solution supply nozzle 31 moves back to the standby position. Simultaneously with the backward movement of the chemical solution supply nozzle 31, the pure water supply nozzle 32 rotates from the standby position to the supply position, that is, the position facing the central portion of the wafer W, and the valve 44 is opened, as shown in FIG. In addition, pure water B is supplied from the pure water supply nozzle 32 to the vicinity of the center of the surface of the wafer W at a flow rate of, for example, 1000 ml / min for 1 minute to rinse the surface of the wafer W. At this time, the cup 20 is lowered by the elevating means 23 and the receiving port 22a of the outer cup 22 is placed at a position facing the peripheral edge of the wafer W, and the pure water scattered from the surface of the wafer W is removed from the receiving port 22a. The air is sucked into the air 22 and discharged through the drain pipe 26.
[0030]
After replacing the hydrofluoric acid solution remaining on the surface of the wafer W with pure water and removing it as described above, the pure water supply nozzle 32 moves back to the standby position. Simultaneously with the retreat of the pure water supply nozzle 32, the moving mechanism 34 is driven to move the N2 gas supply nozzle 33 to the vicinity of the center of the surface of the wafer W and from the center of the surface of the wafer W to the outer periphery. At this time, the valve 45 is opened and N2 gas is supplied (injected) at a flow rate of 240 liters / minute, for example, for 5 seconds, and the N2 gas supply nozzle 33 is moved from the center of the surface of the wafer W at a speed of 20 mm / sec, for example. It moves toward the outer periphery (see FIG. 6C). At this time, the rotation speed of the wafer W is rotated to a maximum of 3000 rpm, for example. As a result, the pure water on the surface of the wafer W cannot be formed into a spherical shape, and is pushed out by the N2 gas in the outer peripheral direction of the wafer W. As shown in FIG. It is removed and a drying process is performed. In this case, when stopping the N2 gas supply nozzle 33, it is preferable to stop it at a position before the outer peripheral end face of the wafer W (for example, a position 10 mm to 20 mm before the outer peripheral end face). This is because if the wafer W is moved to the vicinity of the outer peripheral end surface portion, gas is blown around the wafer W, and particles may be wound up. Thus, the N2 gas supply nozzle 33 is stopped at the stop position, and after a while, the rotation speed of the wafer W starts to be reduced, and the N2 gas supply nozzle 33 starts to move backward. Such a series of processing is performed based on a program that is previously input and stored in the memory of the control unit 40.
[0031]
Next, the relationship between the rotation speed of the wafer W with respect to the processing time in the cleaning method, the position of the N2 gas supply nozzle 33 with respect to the wafer W, and the injection amount of N2 gas will be described with reference to the timing chart shown in FIG. To do. First, the rotation speed of the wafer W is accelerated from the stationary state to 300 rpm from the start of processing 0 to t1, and then is rotated at a constant speed until t2. During the period from t1 to t2, chemical treatment and cleaning are performed, and the N2 gas supply nozzle 33 is moved to the center of the wafer W simultaneously with the retreat of the pure water supply nozzle 32. At t2, acceleration of the rotational speed of the wafer W is started and the movement of the N2 gas supply nozzle 33 is started. Further, the supply of N2 gas is started immediately before the gas injection amount reaches an appropriate value, for example, 50 liters / minute at t2. Further, the acceleration is stopped at t3 when the rotation speed of the wafer W reaches 3000 rpm, and the rotation is made constant speed so as to maintain 3000 rpm. At this time, the N2 gas supply nozzle 33 is moving, but stops moving at t4 when it reaches the stop position, and the supply of N2 gas is also stopped. Thereafter, at t5, the rotational speed of the wafer W is decelerated and the N2 gas supply nozzle 33 is retracted.
[0032]
The liquid processing method according to the present invention is not necessarily based on the above-described cleaning method program, and can be performed based on another cleaning method program. For example, it can be performed based on the program shown in the timing chart shown in FIG. That is, the rotation speed of the wafer W is accelerated from a stationary state to 300 rpm from the start of processing 0 to t1, and then is rotated at a constant speed. Thereafter, the chemical treatment and the cleaning treatment are finished by time t2, and the movement of the N2 gas supply nozzle 33 is started at t2, and the injection amount is set to an appropriate value, for example, 240 liters / minute, which is much higher than the above 50 liters / minute. N2 gas is injected from the N2 gas supply nozzle 33. At time t4, the N2 gas supply nozzle 33 reaches the stop position, and the supply of N2 gas is stopped. In addition, the rotational speed of the wafer W starts to be reduced. Thereafter, after the rotation of the wafer W is stopped, at time t5, the N2 gas supply nozzle 33 starts to move back to the original position.
[0033]
As described above, when a large flow rate of N2 gas is sprayed onto the low-speed rotating wafer W, the wafer W having deep irregularities on the surface can be more reliably dried without generating a watermark.
[0034]
As in the above two examples, N2 gas is supplied from the center of the surface of the wafer W toward the outer periphery while rotating the wafer W after the cleaning process, whereby precipitation of reactants of oxygen and silicon in water, air, Generation of watermarks due to precipitation of silica contained in water can be prevented, generation of particles can be reduced, and yield can be improved.
[0035]
◎ Second embodiment
Next, a second embodiment of the liquid processing apparatus according to the present invention will be described based on the process diagram shown in FIG.
[0036]
In the second embodiment, the lower side of the above-described N2 gas supply nozzle 33 is inclined by an appropriate inclination angle α, for example, about 15 ° from the direction perpendicular to the wafer W to the moving direction of the N2 gas supply nozzle 33. It is a case where it forms. The inclination angle α is preferably in the range of 5 ° to 45 °.
[0037]
In this case, while rotating the spin chuck 10, the N2 gas supply nozzle 33 is gradually inclined from the vertical state in the vicinity of the center of the wafer W, and the inclination movement is stopped when the angle becomes α (FIG. 9 ( a)). Thereafter, the N2 gas supply nozzle 33 is moved to an outer portion of the wafer W at an appropriate speed (see FIG. 9B), and before the outer peripheral end surface portion of the wafer W (for example, about 10 to 20 mm before the outer peripheral end surface portion). The movement of the N2 gas supply nozzle 33 is stopped when it reaches the position (see FIG. 9C). In this case, the scanning movement speed of the N2 gas supply nozzle 33 is preferably 20 ± 5 mm / second. The distance from the jet outlet at the tip of the N2 gas supply nozzle 33 to the surface of the wafer W is preferably in the range of 10 to 20 mm. Further, the diameter of the jet outlet at the tip of the N2 gas supply nozzle 33 is preferably in the range of 4 to 16 mm.
[0038]
Further, the N2 gas supply nozzle 33 may be inclined by an angle α from the beginning. In that case, it is necessary to perform alignment so that the initially injected N2 gas blows the central portion of the wafer W.
[0039]
In addition, since the other part of 2nd embodiment is the same as that of said 1st embodiment, the same code | symbol is attached | subjected to the same part and the description is abbreviate | omitted.
[0040]
With this configuration, the cleaning liquid on the wafer W can be removed more effectively, and the generation of watermarks can be further reliably reduced.
[0041]
◎ Third embodiment
Next, a third embodiment of the present invention will be described based on the process diagram shown in FIG.
[0042]
The third embodiment is a case where it is possible to improve the drying efficiency and reduce the consumption of the inert gas. That is, first, as in the first and second embodiments, a chemical solution such as hydrofluoric acid solution A is supplied from the chemical solution supply nozzle 31 with the wafer W set to a predetermined rotational speed, eg, 300 rpm, to remove the natural oxide film on the surface of the wafer W. (See FIG. 10A). Next, pure water B is supplied from the pure water supply nozzle 32 to the surface of the wafer W to rinse the surface of the wafer W (see FIG. 10B).
[0043]
After replacing the hydrofluoric acid solution remaining on the surface of the wafer W with pure water and removing it as described above, the pure water supply nozzle 32 moves back to the standby position. Next, the wafer W is rotated at high speed (for example, 3000 rpm), and pure water adhering to the surface of the wafer W is shaken off by the action of centrifugal force (see FIG. 10C).
[0044]
Next, N2 gas is supplied (injected) while moving the N2 gas supply nozzle 33 from the center of the surface of the wafer W toward the outer periphery (see FIG. 10D) to remove pure water on the surface of the wafer W. (Dry) (see FIG. 10E).
[0045]
As described above, the amount of pure water adhering to the surface of the wafer W can be reduced by rotating the wafer W at a high speed after the cleaning process with pure water and shaking off the pure water on the surface of the wafer W. Therefore, it is possible to improve the drying efficiency by the subsequent injection of N2 gas and reduce the consumption of N2 gas.
[0046]
In the above description, the N2 gas supply nozzle 33 is moved in the vertical state. However, the N2 gas supply nozzle 33 may be inclined as in the second embodiment.
[0047]
The cleaning apparatus configured as in the first to third embodiments is used alone or in a semiconductor wafer cleaning processing system as described below. As shown in FIG. 11, the semiconductor wafer cleaning processing system has a wafer W loading / unloading port 50 on which a cassette C containing a plurality of, for example, 25 wafers W to be processed is transported and placed from the outside. A transfer arm 51 movable in the horizontal (X, Y) direction and rotation (θ) direction, and a main arm 52 movable in the Y, θ and Z (height) directions. Further, in this cleaning processing system, a back surface cleaning unit 54, a cleaning / drying unit 55, and an APM processing unit 56 are arranged on one side along the conveyance path 53 of the main arm 52, and the other side along the conveyance path 53. On the side, an HPM processing unit 57 and a hydrofluoric acid processing unit 58 which is a liquid processing apparatus according to the present invention are arranged.
[0048]
In the cleaning processing system configured as described above, the processing procedure will be described based on the flowchart shown in FIG. First, an appropriate program according to the properties of the thin film on the surface of the wafer W to be processed is input in advance into the memory of the control unit 40 and stored (S1). The wafers W in the cassette C loaded into the loading / unloading port 50 are transferred to the main arm 52 via the transfer arm 51 and sequentially transferred to the processing units. That is, the wafer W is first cleaned by the back surface cleaning unit 54 with the cleaning liquid such as pure water (S2), and then the APM processing unit 56 mixes the APM solution (ammonia, hydrogen peroxide and pure water). Particles are removed by the solution. The wafer W that has been subjected to APM processing is subsequently cleaned of metal contamination by an HPM solution (mixed solution of hydrochloric acid, hydrogen peroxide solution, and pure water) in the HPM processing unit 57 (S3). Further, after the wafer W is carried into the hydrofluoric acid processing unit 58 by the main arm 52 (S4), the spin chuck 10 is rotated at a rotational speed of, for example, 300 rpm (S5). Thereafter, as described above, the natural oxide film is removed by the hydrofluoric acid solution (S6), and the hydrofluoric acid solution remaining on the surface of the wafer W is replaced with pure water by supplying pure water, thereby replacing the hydrofluoric acid solution. After removing (S7), while the wafer W is rotated at 300 rpm, N2 gas is supplied from the center of the surface of the wafer W toward the outer periphery to perform a drying process (S8). Then, the rotation of the wafer W is stopped (S9), and the wafer W is unloaded from the hydrofluoric acid processing unit 58 (S10). After the treatment as described above, finally, it is finally washed with pure water in the washing and drying unit 55 and dried. In the above processing procedure, the liquid processing method according to the present invention has been described based on the program shown in FIG. 8, but may be performed based on the program shown in FIG.
[0049]
In the above-described embodiment, the case where the liquid processing apparatus according to the present invention is applied to a semiconductor wafer cleaning apparatus has been described. However, the liquid processing apparatus is not necessarily limited to semiconductor wafer cleaning. Of course, it can be applied to the above. Further, a patterned thin film such as a silicon oxide film, a silicon nitride film, or a polysilicon film may be formed on the surface of the object to be processed, or chemical mechanical polishing (not formed with a thin film) ( It may be a smooth surface that has been subjected to chemical mechanical polishing. Furthermore, although the case where the chemical solution is a hydrofluoric acid solution has been described in the above description, a chemical solution other than the hydrofluoric acid solution may be used, and in the above embodiment, the case where the inert gas is N2 gas has been described. It is also possible to select and use one or more kinds of gases from N2 gas and other inert gases such as Ar, He, CO2 and air.
[0050]
【Example】
Next, an example of an embodiment of the present invention, Comparative Example 1 in which a drying process is performed without using an inert gas, and a drying process by supplying an inert gas to the center of the object to be processed, for example, the wafer W, are performed. The result of an experiment for examining the remaining amount of watermark remaining on the surface of the wafer W by comparing with Comparative Example 2 to be performed will be described.
[0051]
★ Experimental conditions
(1) Concentration of hydrofluoric acid solution
Hydrofluoric acid solution (50% by weight): Water = 1: 10
(2) Processing process
After hydrofluoric acid treatment, rinse with pure water, and then dry by spin drying or N2 gas supply
(3) Sample to be evaluated
8-inch wafer; 0.8 μm line and space pattern of the cross-sectional structure of FIG.
(4) Watermark measurement method
Measuring instrument: Metallic microscope [Olympus Engineering Co., Ltd.]
Measurement magnification: × 200 (eyepiece × 10, objective × 20)
(5) Examples
・ N2 gas flow rate: 240 liters / minute
・ Scanning speed of N2 gas supply nozzle: 20mm / sec
・ Wafer rotation speed: Maximum 3000rpm
・ Discharge time: 5 seconds
Comparative Example 1
・ Wafer rotation speed: Maximum 3000rpm
Comparative Example 2
・ N2 gas supply rate: 240 liters / minute
-Wafer rotation speed: Maximum 3000 rpm.
[0052]
As shown in FIG. 13, the number of watermarks in a 9-point 5 mm square chip on the wafer W was examined as shown in FIG. As shown, the number of watermarks at each point was zero. On the other hand, in Comparative Example 1 in which the drying is performed only by rotating the wafer W without supplying N2 gas, as shown in FIG. 13B, the number of watermarks at each point is 3 digits. The average number of watermarks per point was 94.1 pieces / chip. Further, in Comparative Example 2 in which N2 gas is supplied to the center of the wafer W and dried, a watermark remains on the center side of the wafer W as shown in FIG. The number of watermarks was 3.4 / chip.
[0053]
【The invention's effect】
As described above, according to the present invention, since it is configured as described above, the following effects can be obtained.
[0054]
1) Claims 1, 7 According to the described invention, the inert gas is supplied from the center of the object to be processed toward the outer periphery while rotating the object to be processed, and the cleaning liquid remaining on the surface of the object to be processed is positively removed and dried. Since this can be done, the occurrence of watermarks can be reduced. In addition, since the cooled inert gas is supplied to remove the cleaning liquid remaining on the surface of the object to be processed, the speed of the chemical reaction that causes the watermark can be reduced. Therefore, for example, precipitation of silica in the pure water and precipitation of the reaction product do not substantially occur, the generation of watermarks and particles can be reduced, and the yield can be improved.
[0055]
2) Also, The cleaning liquid is supplied to the surface of the object to be processed while rotating the object to be processed, and then the inert gas is supplied from the center of the object to be processed toward the outer periphery while rotating the object to be processed. Since the remaining cleaning liquid can be actively removed and dried, the generation of watermarks can be reduced. Further, by stopping at a position before the outer peripheral end surface portion of the object to be processed, it is possible to eliminate the possibility of rolling up particles without blowing an inert gas around the object to be processed.
[0056]
3) Claims 2, 3, and 4 According to the described invention, the inert gas supply means is scanned and moved while accelerating the rotation of the object to be processed, and the inert gas is supplied from the inert gas supply means to the surface of the object to be processed. In addition to 2), the drying time can be shortened and the drying efficiency can be improved.
[0057]
4) Claims 5 and 8 According to the described invention, the inert gas supply means is tilted with respect to the surface of the object to be processed, and the inert gas is supplied while supplying the inert gas in the direction in which the inert gas supply means tries to scan and move. Since the inclined inert gas holding means can remove the cleaning liquid on the surface of the object to be processed more effectively by scanning the supply means, in addition to the above 1) and 2), the generation of watermarks and the generation of particles Generation can be reduced.
[0058]
5) Claims 6, 9 According to the described invention, the inert gas supply means is gradually inclined from the vertical state in the vicinity of the center of the object to be processed, and is scanned after the predetermined angle is reached. The alignment of the active gas supply means can be facilitated.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part when a first embodiment of a liquid processing apparatus according to the present invention is applied to a semiconductor wafer cleaning apparatus;
FIG. 2 is a schematic plan view of FIG.
FIG. 3 is a schematic configuration diagram illustrating a chemical liquid supply nozzle, a cleaning liquid supply nozzle, an inert gas supply nozzle, and a control unit thereof according to the present invention.
4 is an enlarged plan view of a main part of FIG.
FIG. 5 is a side view of FIG. 4;
FIG. 6 is a process diagram showing a processing procedure of the present invention.
FIG. 7 is a timing chart showing the relationship among the number of wafer rotations with respect to processing time, the position of an N 2 gas supply nozzle with respect to the wafer, and the N 2 gas injection speed in an example of a liquid processing method according to the present invention;
FIG. 8 is a timing chart showing the relationship among the number of rotations of the wafer with respect to the processing time, the N 2 gas supply nozzle for the wafer, and the N 2 gas injection speed in another example of the liquid processing method according to the present invention.
FIG. 9 is a process diagram showing a processing procedure according to the second embodiment of the present invention.
FIG. 10 is a process diagram showing a processing procedure according to the third embodiment of the present invention.
FIG. 11 is a schematic plan view showing a semiconductor wafer cleaning system incorporating the liquid processing apparatus according to the present invention.
FIG. 12 is a flowchart showing a processing procedure of a semiconductor wafer cleaning processing system incorporating a liquid processing apparatus according to the present invention;
FIG. 13 is an explanatory diagram showing the results of cleaning evaluation for Examples and Comparative Examples of the present invention.
FIG. 14 is a process diagram showing a conventional cleaning method.
FIG. 15 is an enlarged sectional view showing an example of a surface structure of a wafer to be cleaned.
[Explanation of symbols]
A Hydrofluoric acid solution (chemical)
B Pure water (cleaning liquid)
W Semiconductor wafer (object to be processed)
10 Spin chuck (rotation holding means)
31 Chemical supply nozzle (chemical supply means)
32 Pure water supply nozzle (cleaning liquid supply means)
33 N2 gas supply nozzle (inert gas supply means)
34 Movement mechanism
40 Control unit

Claims (9)

Supplying and cleaning the surface of the object to be processed while rotating the object to be processed held by the rotation holding means disposed in the cup ; and
Supplying an inert gas cooled toward the outer periphery from the center of the surface of the object to be processed while rotating the object to be processed, and
A liquid processing method comprising: stopping scanning movement of an inert gas supply means and supplying inert gas at a position before the outer peripheral end face of the object to be processed , and then stopping rotation of the object to be processed. In the liquid processing method of Claim 1,
A liquid processing method, wherein the inert gas supply means is scanned and moved while accelerating the rotation of the object to be processed, and the inert gas is supplied from the inert gas supply means to the surface of the object to be processed. In the liquid processing method of Claim 2,
The supply of the inert gas is started immediately before the rotation acceleration of the object to be processed, and the start of the rotation acceleration and the start of the scan movement of the inert gas supply means are substantially simultaneously, and the scan of the inert gas supply means is performed. A liquid processing method characterized in that the rotational acceleration of the object to be processed is terminated during movement. In the liquid processing method of Claim 2,
The supply of the inert gas is started immediately before the rotation acceleration of the object to be processed, and the rotation acceleration of the object to be processed and the start of the scan movement of the inert gas supply means are substantially simultaneously, A liquid processing method comprising: ending the scan movement of the inert gas supply means when the object to be processed is rotated at a constant speed after the completion. In the liquid processing method in any one of Claim 1 thru | or 4,
Inclining the gas outlet of the inert gas supply means with respect to the surface of the object to be processed, and scanning the inert gas supply means while supplying the inert gas in the direction in which the inert gas supply means intends to scan. A liquid processing method characterized by the above. In the liquid processing method of Claim 5,
A liquid processing method, wherein the inert gas supply means is gradually inclined from the vertical state in the vicinity of the center of the object to be processed, and is scanned after a predetermined angle is reached. A rotatable rotation holding means disposed in the cup and holding the object to be processed;
Cleaning liquid supply means for supplying a cleaning liquid to the surface of the object to be processed;
An inert gas supply means for supplying an inert gas to the surface of the object to be processed;
A moving mechanism for scanning the inert gas supply means from the center of the object to be processed toward the outer periphery;
Cooling means for cooling the temperature of the inert gas supplied to the object to be processed;
Control means for controlling rotation of the rotation holding means, scan movement of the inert gas supply means, and supply of inert gas ;
Based on the signal from the control means, the scanning movement of the inert gas supply means and the supply of the inert gas are stopped at a position before the outer peripheral end surface of the object to be processed , and then the rotation of the object to be processed is stopped. made by forming on so that is, liquid processing apparatus, characterized in that. In the liquid processing apparatus of Claim 7,
A liquid processing apparatus, wherein the gas outlet of the inert gas supply means is inclined toward the scanning movement direction of the inert gas supply means. In the liquid processing apparatus of Claim 8,
Based on the signal of the control means, the inert gas supply means is formed so as to be gradually inclined from the vertical state in the vicinity of the center of the object to be processed, and to be moved by scanning after reaching a predetermined angle. A liquid processing apparatus.

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