JP4165845B2 - Surface treatment method and cleaning apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface processing method for finely processing the surface of an object to be processed such as an LSI (semiconductor device), an LCD (liquid crystal display device), a PDP (plasma display panel) or the like, and a cleaning used in the processing. More particularly, the present invention relates to a surface treatment method and a cleaning apparatus capable of removing a fence-like residue generated by metal etching.
[0002]
[Background technology]
Along with the high integration of LSIs and the like, design rules have been miniaturized. As a result, wiring delay due to an increase in internal resistance has become a problem. In the memory field, it is a problem to secure a charge storage capacity that is contrary to the reduction of the cell area. Furthermore, a memory called a ferroelectric memory and having a feature of non-volatility has been newly developed.
As a wiring material or an electrode material in such semiconductor devices such as LSI and memory, platinum (Pt), iridium (Ir) instead of conventional materials such as aluminum (Al), aluminum alloy, and polysilicon (Si). Noble metals such as low resistance copper (Cu) are being used.
However, since noble metals and copper are refractory metals, many problems occur when dry etching is performed on semiconductor devices that have them on the surface, and one of them is fence-like residue (sidewall deposition). ). First, this will be described.
[0003]
In a manufacturing process of a semiconductor device or the like, a lithography process and an etching process are a series of processes, and after application of a resist, pattern exposure by a stepper, and development, the base material is etched using the resist as a mask. In addition, dry etching is preferred for fine processing etching, and dry etching is generally performed by high-density plasma using a mixed gas of a reactive gas and a non-reactive gas such as argon gas. In the precious metal etching process performed on the semiconductor substrate, for example, when Pt, Ir, or the like is used as an electrode material for a semiconductor device or the like, the reaction gas is mainly halogen such as chlorine gas, chloride gas, fluoride gas, or the like. A chemical gas is used.
[0004]
However, noble metal halides have low volatility, and noble metal compounds typified by halides generated by etching reattach to the side walls of the resist mask, and a fence-like residue remains on the pattern even after ashing. Such a fence-like residue may be referred to as a rabbit ear because of its shape. This sidewall deposit is known to be formed of PtClxOy or a mixture of PtClx and PtOy when etching is performed with chlorine gas, for example, using Pt as an electrode material.
[0005]
[Prior art]
Conventionally, altered films and polymers that remain after etching a metal-based material such as Al on the surface of an object such as a silicon wafer are removed by dipping the wafer in an amine-based stripper after ashing.・ Was washing. That is, when the etching process for performing the etching process for volatilizing the metal on the surface of the object to be processed is performed using a dry etching apparatus such as a plasma etcher, the object to be processed is removed in addition to the ashing process. The cleaning process was performed using a cleaning device equipped with a cleaning tank for holding the stripping solution.
[0006]
However, after etching with Pt and Ir, a fence-like residue is generated in addition to the altered film, and this cannot be removed by cleaning with a stripping solution using a conventional dip. In view of this, for example, a method has been devised for removing the deposits on the sidewalls by a wet etching method using an acid such as hydrochloric acid (see, for example, JP-A-8-45905). That is, when a dry etching process for performing an etching process for volatilizing the metal on the surface of the object to be processed is performed, and a fence-like residue, that is, a side wall deposit is generated, an ashing process and an object to be processed are thereafter performed. In addition to the washing step of washing with a stripping solution, a wet etching step of treating an object to be treated with an acid using another wet apparatus has come to be performed.
[0007]
[Problems to be solved by the invention]
However, in the method of removing sidewall deposits by wet etching with acid, it is difficult to completely remove deposits in a fine pattern, and in addition, film peeling of the electrode itself and acid other than the capacitor structure can be removed. Undesirable results such as short wiring due to erosion and deterioration of characteristics of the interlayer insulating film may occur. In addition, the number of processes increases due to the addition of new processes such as the addition of wet etching to plasma etching, which may lead to an unfavorable situation such as a prolonged series of processing periods and difficulty in maintaining throughput. Derive.
[0008]
Therefore, the surface treatment method has been devised so that the side wall deposits generated by metal etching can be accurately removed without increasing the number of processes other than the cleaning process after etching and ashing and without damaging the object to be processed. It becomes a problem to do. It is also a problem to devise an apparatus suitable for such processing.
The present invention has been made to solve such a problem, and an object of the present invention is to realize a surface treatment method capable of accurately removing sidewall deposits.
Another object of the present invention is to realize a cleaning apparatus that can accurately remove sidewall deposits.
[0009]
[Means for Solving the Problems]
About the 1st thru | or 5th solution means invented in order to solve such a subject, the structure and effect are demonstrated below.
[0010]
[First Solution]
The surface treatment method of the first solution means (as described in claim 1 at the beginning of the application) is an etching treatment for volatilizing the metal on the surface of the object to be treated (by gas phase reaction in plasma or the like). A surface provided with an etching step for performing a cleaning process and a cleaning step for washing the object to be treated (at least the surface to be cleaned) with a stripping solution (in a state immersed in) after that (with or without an ashing step) In the processing method, the cleaning step is performed with irradiation of ultrasonic waves toward the object to be processed.
[0011]
In such a surface treatment method of the first solving means, the object to be treated is cleaned with a stripping solution after being subjected to an etching process, and ultrasonic waves are also irradiated during the cleaning.
As a result, even when a fence-like residue is generated on the surface of the object to be processed due to the volatilization of the metal during etching, the ultrasonic wave is removed almost simultaneously with the removal of the resist and the resist burns with the stripper along with the subsequent cleaning. The fence-like residue is also removed by the stimulation. At that time, in addition to the original direct action on the resist or the like, the stripping solution serves as a medium for propagating ultrasonic waves, and can also be said to be useful as an auxiliary accelerator for speeding up the cutting of the base of the fence-like residue. .
[0012]
Such a surface treatment method is accompanied by quality improvement of the cleaning process, but does not add a new separate process to the combination of the etching process and the cleaning process.
Therefore, according to the present invention, it is possible to realize a surface treatment method capable of removing sidewall deposits without increasing the number of steps.
[0013]
[Second Solution]
A surface treatment method of the second solution means (as described in claim 2 at the beginning of the application) is the surface treatment method of the first solution means, wherein the number of oscillations of the ultrasonic wave is the same as that of the stripping solution. It is characterized by exceeding the resonance frequency.
[0014]
In such a surface treatment method of the second solving means, cavitation in which ultrasonic stimulation applied to the object to be processed for removing the fence-like residue frequently occurs due to resonance between the ultrasonic wave and the medium. It is not an impact caused by the vibration, and it becomes a finer vibration.
Since such fine vibrations are weakly irritating, they do not damage general structures on the surface of the object to be processed and relatively flat formed objects. On the other hand, the fence-like residue resembling ridges and walls has a certain amount of shaking, and the bending force is concentrated at the base, so the fence-like residue can be easily removed from the base with the aid of the stripping solution. Cut out.
[0015]
As a result, the surface of the object to be processed is not subjected to an undesirably strong stimulus except for the fence-like residue, and the fence-like residue is surely removed.
Therefore, according to the present invention, it is possible to realize a surface treatment method capable of removing the sidewall deposit without increasing the number of steps and without damaging the workpiece.
[0016]
[Third Solution]
The cleaning device of the third solution means (as described in claim 3 at the beginning of the application), and the object to be processed (the whole or a part of the main surface, etc.) (stationary or with reflux or inflow / outflow) In a cleaning apparatus provided with a means for immersing in a stripping liquid (in a fluid state), an ultrasonic irradiation means for emitting ultrasonic waves having an oscillation frequency exceeding the resonance frequency with the stripping liquid is provided toward the object to be processed. .
[0017]
In such a cleaning apparatus of the third solution, the object to be processed is irradiated with ultrasonic waves while being immersed in the stripping solution. Moreover, the number of oscillations of the ultrasonic wave exceeds the resonance frequency with the stripping solution.
As a result, the cleaning process of washing the object to be processed with the stripping solution is performed with the irradiation of ultrasonic waves toward the object to be processed, and the number of ultrasonic oscillations exceeds the resonance frequency with the stripping liquid. . Therefore, the first and second solving means described above can be implemented by using this cleaning device.
Therefore, according to the present invention, it is possible to realize a cleaning apparatus that can remove the side wall deposits without increasing the number of steps and without damaging the object to be processed.
[0018]
[Fourth Solution]
The cleaning device of the fourth solution means (as described in claim 4 at the beginning of the application) is the cleaning device of the third solution means, wherein the object to be treated (directly held or separately) Rotation drive means for rotating while being immersed in the stripping solution (via a holding means).
[0019]
The stimulus to the fence-like residue is isotropic in the case of cavitation that repeatedly occurs and disappears in the medium, whereas when ultrasonic waves with an oscillation frequency exceeding the resonance frequency with the stripping solution are irradiated, the ultrasonic waves The anisotropy corresponding to the traveling direction or the irradiation direction becomes stronger. Also, the bending rigidity and strength of the fence-like residue are anisotropic.
[0020]
On the other hand, in the cleaning device of the fourth solving means, the object to be processed is rotated while being immersed in the stripping solution. Then, along with the rotation, the relative positional relationship between the surface of the object to be processed and the ultrasonic traveling direction or the like makes at least one turn.
Thereby, even if it is a fence-like residue which turned to which direction, the strong irritation | stimulation by a coincidence of directionality will be received reliably.
Therefore, according to the present invention, it is possible to realize a cleaning apparatus that can reliably remove the side wall deposits without increasing the number of steps and without damaging the workpiece.
[0021]
[Fifth Solution]
A surface treatment method and a cleaning apparatus according to a fifth solution means (as described in claim 4 at the beginning of the application) are the cleaning apparatuses according to the third solution means, wherein ultrasonic waves directed toward the object to be processed are used. A means for making (at least) a round of the traveling direction or the irradiation direction is provided.
[0022]
In such a cleaning apparatus of the fifth solving means, when the object to be processed is washed with the stripping solution, the traveling direction or the irradiation direction of the ultrasonic wave directed to the object to be processed is completed. Whether continuous or discrete, 360 ° is covered if at least the trajectories are overlapped. Then, along with the round, the relative positional relationship between the surface of the object to be processed and the ultrasonic traveling direction is at least rounded.
Thereby, even if it is a fence-like residue which faced to which direction, the strong stimulation of the ultrasonic wave based on a coincidence of directionality will be received reliably.
Therefore, according to the present invention, it is possible to realize a cleaning apparatus that can reliably remove the side wall deposits without increasing the number of steps and without damaging the workpiece.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
About the surface treatment method and the cleaning apparatus of the present invention achieved by such a solution, specific modes for carrying out this will be described with reference to the following first to sixth embodiments.
The first embodiment shown in FIGS. 1 to 3 embodies the first, second, and third solving means described above, and the second embodiment shown in FIG. The third, fourth, and fifth embodiments shown in FIGS. 5, 6, and 7, respectively, embody the fifth solving means described above. It is. Further, the sixth embodiment shown in FIG. 8 embodies the above-described fourth solving means. The first to fifth embodiments are of a batch type, while the sixth embodiment is of a sheet format.
[0024]
[First embodiment]
A specific configuration of the cleaning apparatus of the present invention used in the surface treatment method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the basic structure of the cleaning device, in which (a) is a plan view and (b) is a front view in a longitudinal state. In the illustration, for the sake of simplicity, only the main part is shown, and a housing that is adequate, a base part such as a base, a support member such as a frame, an exterior member such as a cover, a fastener such as a bolt, A holding member such as a suspension arm of the inner tub, a movable mechanism such as an elevator for lifting and lowering, a controller including a microprocessor, a power source, etc. are omitted.
[0025]
The cleaning apparatus 10 includes a double cleaning tank including an outer tank 11 and an inner tank 14 as means for immersing a plurality of wafers 20 (objects to be processed) in the stripping solution 15.
The outer tub 11 is provided with an ultrasonic vibrator 12 on the inner bottom, and can operate the ultrasonic vibrator 12 in a state where pure water 13 is stored.
The inner tank 14 is made of quartz that allows ultrasonic waves to pass through. The wafers 20 are vertically arranged and accommodated between inner grooves and partition members formed at appropriate intervals, and the wafers 20 are hidden to such a depth that they can be hidden. There is enough depth to store the stripping solution 15.
As a result, the cleaning device 10 includes a cleaning tank that indirectly holds the stripping liquid through an inner tank or the like by an amount that allows the entire workpiece to be immersed.
[0026]
The ultrasonic transducer 12 is preferably one that vibrates at a relatively high frequency from 700 kHz to 2 MHz, for example, a high frequency of 950 kHz. In an ordinary ultrasonic cleaning apparatus, an ultrasonic wave of several tens of kHz that moves solution molecules vigorously is frequently used. In the latter case, a dense part and a sparse part are formed unevenly, and cracks in a vacuum state occur between solution molecules. In other words, cavitation occurs when the frequency of the ultrasonic wave is close to the resonance frequency with the medium, but the movement of solution molecules and the energy at the time of cavitation generation / extinguishing are transmitted to the wafer surface in the solution, indirectly causing dust (particles) and The protrusion is shaken. Although it is effective for a large object of several μm size or more, vibration energy is also transmitted to the wafer itself, so that damage to the wafer may occur when a strong ultrasonic wave is irradiated for a long time.
[0027]
On the other hand, in the former case, that is, in the case of 950 kHz ultrasonic waves emitted from the ultrasonic vibrator 12, the frequency is too high and the solution molecules cannot follow the vibrations very much. Because of the interaction with the smaller solid in relation to the resonance frequency, it is effective for dust and protrusions of about 0.2 to 2.0 μm, and the solid of that size directly receives vibration energy. And the size of the fence-like residue which is the removal target also matches it. On the other hand, the interaction with the wafer itself is relatively small and the wafer damage is small. From this viewpoint, the frequency of the ultrasonic transducer 12 is determined.
[0028]
When the ultrasonic transducer 12 is operated, the generated ultrasonic waves 12 a are sequentially propagated with the pure water 13, the inner tank 14, and the stripping solution 15, thereby vibrating the component molecules of the stripping solution surrounding the wafer 20.
As a result, the cleaning apparatus 10 emits ultrasonic waves 12 a having an oscillation frequency exceeding the resonance frequency with the stripping solution 15 toward the cleaning tanks 11 and 14 and toward the wafer 20 therein. A sound wave irradiation means 12 is provided.
[0029]
Regarding the cleaning apparatus of the first embodiment, the surface treatment method using the same and the operation at that time will be described with reference to the drawings. FIG. 2 is a schematic diagram related to a metal etching process and the like in the surface treatment method, and shows a formation process of a fence-like residue. Moreover, FIG. 3 is a schematic diagram regarding the cleaning step in the surface treatment method, and shows a removal state of the fence-like residue by ultrasonic cleaning in the stripping solution.
Pt and Ir were subjected to plasma etching with a high-density plasma etching apparatus, and after an ashing process, fence-like residues were removed with the cleaning apparatus 10 using the stripping solution 15 as a cleaning solution. Hereinafter, the processing procedure etc. are explained in full detail.
[0030]
The wafer 20 (see FIG. 2A) is formed by laminating an oxide film 22 and titanium 23 (Ti) on the main surface of the silicon wafer 21, and further sputtering platinum 24 (Pt), and then applying a resist 25. The pattern is exposed with a stepper and then developed to form a resist mask (see FIG. 2B).
For example, such a wafer 20 is put into a plasma etcher described in Japanese Patent Application No. 10-56060, and a high-density plasma 24a is generated by a mixed gas of argon and chlorine gas, whereby high-density plasma etching is performed on the wafer 20. (See FIG. 2B). Then, the platinum 24 and the titanium 23 are removed from the surface portion exposed to the high-density plasma 24 a except where they are hidden under the resist 25, but the volatilized part is reattached to the side wall portion of the resist 25. Thus, the fence-like residue 26 grows (see FIG. 2C).
[0031]
Then, resist ashing is performed with a barrel-type asher. That is, the wafer 20 is exposed to the oxygen plasma 25a (see FIG. 2C).
Thus, the resist 25 is removed, and the electrode pattern and wiring pattern of the platinum 24 are formed. However, the fence-like residue 26 remains on the platinum 24 (see FIG. 2D). The fence-like residue 26 protrudes upward from the upper corners of the platinum 24, extends along the pattern, and changes its direction together with the pattern.
A fence-like residue is formed through such a metal etching process.
[0032]
Next, the wafer 20 is cleaned using the cleaning apparatus 10 (see FIG. 3). An appropriate number of wafers 20 are accommodated in the inner tank 14 and the stripping solution 15 is sufficiently poured, and then the inner tank 14 is put into the outer tank 11 filled with pure water 13 (see FIG. 1). Thus, when the workpiece 20 is immersed in the stripping solution 15 (see FIG. 3A), the ultrasonic transducer 12 is operated by operating an operation unit (not shown). Then, the ultrasonic wave 12a propagates in the stripping solution 15 along the main surface of the wafer 20, and reaches the pattern of the platinum 24 and the fence-like residue 26 thereon (see FIG. 3A).
[0033]
Then, the vibration of the ultrasonic wave 12a stimulates and shakes the fence-like residue 26. At the same time, when the stripping solution 15 removes debris at the base, the fence-like residue 26 is separated from the platinum 24 one after another (FIG. 3). (See (b)). At that time, the remaining platinum 24 is also irradiated with the ultrasonic wave 12a, but this only removes particles and the like adhering to the surface, and there is no damage.
In this way, the workpiece 20 is washed with the stripping solution 15 with high frequency ultrasonic irradiation.
[0034]
In this cleaning, the temperature of the stripping solution used was room temperature and the stripping time was 40 minutes. Here, the cleaning time can be shortened by increasing the temperature of the stripping solution. The power of the ultrasonic transducer 12 is 600W. After cleaning with the stripping solution, isopropyl alcohol (IPA) cleaning and pure water cleaning were performed, and the stripping solution was washed away and further dried.
Thus, when the wafer 20 after the cleaning process was observed by cross-sectional SEM observation and the effect of peeling was confirmed, the fence-like residue 26 was clearly removed from the surface of the wafer 20 (see FIG. 3C). .
[0035]
Even if the same ultrasonic cleaning is performed, the solution is less effective with pure water or acid, and it is effective for each stage to use a stripping solution as the solution.
Here, in order to fully exhibit the stripping effect of the stripping solution, it is preferable to combine monoethanolamine and pure water. As a specific example, the blending effect of 50% monoethanolamine, 10% pyrocatechol, and 40% pure water has a very high peeling effect. More preferably, all of the above components are provided, and dimethyl sulfoxide is added as a solvent at about 50% of the total solution. Examples of other solvents include N-methylpyrrolidone. Furthermore, commercially available stripping solutions containing an amine component and water are easy to use.
[0036]
As another specific example, the same effect was obtained when Ir was sputtered on a Si wafer on which an oxide film, Ti, and iridium oxide were stacked, a resist mask was formed, and a similar peeling experiment was performed. That is, the fence-like residue could be removed cleanly.
The same applies to the etching gas, and even when argon single gas, argon and bromide gas, fluoride gas or chloride gas are used, a fence-like residue is formed, but the resist stripping solution and high vibration ultrasonic waves It was confirmed that the residue could be removed by the combination.
[0037]
As is apparent from the above description, according to the present invention, fence-like residues generated in plasma etching of noble metals such as Pt and Ir can be easily removed by using a resist stripping solution and high-vibration ultrasonic waves in combination. can do. In addition, as an order, washing after ashing is not different from a normal sequence, so that it matches the existing process and does not hinder the throughput.
[0038]
[Second embodiment]
About the 2nd Example of the washing | cleaning apparatus of this invention, the specific structure is described with reference to drawings. 4A and 4B are schematic views showing the basic structure, in which FIG. 4A is a plan view and FIG. 4B is a front view in a longitudinal state.
[0039]
The cleaning device 40 is different from the above-described cleaning device 10 in that the ultrasonic transducer 12 is moved to the inner side surface (left side in FIG. 4) of the outer tank 11 and the inner tank 14 is vertical. A point corresponding to this, the point where the wafers 20 are arranged vertically in a horizontal state, and a point where a motor 41 and the like are additionally provided.
Since the inner tank 14 is closed at the bottom and side surfaces so that the stripping solution 15 can be stored, the wafer 20 is temporarily placed on a rack formed by a net-like wire (not shown), a synthetic resin such as Teflon, quartz, or the like. After being stored one by one, the entire net-like shelf is collected and stored in the inner tank 14.
Accordingly, the cleaning device 40 includes the holder 14 that holds the workpiece 20 in the cleaning tank 11.
[0040]
The motor 41 is attached to a suspension arm or the like (not shown) of the inner tub 14, and the rotation of its output shaft is transmitted to the inner tub 14 via an appropriate coupling 42 and shaft 43.
Accordingly, the cleaning device 40 includes a rotation driving unit 41 that rotates the holder 14 in the cleaning tank 11 to rotate the workpiece 20 while being immersed in the stripping solution 15.
[0041]
In this case, when cleaning the wafer 20, the ultrasonic wave 12 a is irradiated, and at the same time, the inner tank 14 rotates gently.
When the inner tank 14 is rotated once or more, the fence-like residue present on the main surface of the wafer 20 is shaken from the side at least once, regardless of the direction, and is strong against this stimulation. Sensitive and separated.
In this way, all fence-like residues are reliably removed.
[0042]
[Third embodiment]
The specific configuration of the third embodiment of the cleaning apparatus of the present invention will be described with reference to the drawings. 5A and 5B are schematic views showing the basic structure, in which FIG. 5A is a plan view and FIG. 5B is a front view in a longitudinal state.
[0043]
This cleaning device 50 in FIG. 5 is different from the cleaning device 40 in FIG. 4 in that the ultrasonic transducer 12 is moved to the inner side surface (to the left in FIG. 4) of the newly introduced rotary rod 54. A motor 51 or the like connected to the rotary rod 54 is introduced instead of the motor 41 or the like connected to the inner tank 14.
The rotating basket 54 is a cylindrical bowl smaller than the outer tank 11 and larger than the inner tank 14, and is supported so as to be rotatable around the inner tank 14 in the outer tank 11. The rotation of the motor 51 is transmitted via the coupling 52 and the shaft 53.
[0044]
In this case, when the wafer 20 is cleaned, the ultrasonic wave 12a is irradiated, and at the same time, the rotary rod 54 rotates gently. Then, as the rotary rod 54 rotates, the ultrasonic transducer 12 rotates around the inner tank 14 while facing the inner tank 14, so that the irradiation direction of the ultrasonic wave 12a also changes continuously.
As a result, the cleaning device 50 is provided in addition to the ultrasonic irradiation means 12 and moves toward the object to be processed in the cleaning tank by rotating the traveling direction or irradiation direction of the ultrasonic waves 12a in the cleaning tanks 11 and 14. At least one round of the traveling direction or irradiation direction of the ultrasonic wave is made.
[0045]
When the rotary rod 54 is rotated once or more, the fence-like residue present on the main surface of the wafer 20 is shaken from the side at least once, regardless of the direction, and is strong against this stimulation. Sensitive and separated.
Thus, in this case as well, all fence-like residues are reliably removed.
[0046]
[Fourth embodiment]
A specific configuration of the fourth embodiment of the cleaning apparatus of the present invention will be described with reference to the drawings. FIG. 6 is a plan view schematically showing the basic structure.
[0047]
This cleaning device 60 in FIG. 6 differs from the cleaning device 40 in FIG. 4 in that the ultrasonic transducer 12 is provided on all the inner surfaces (four sides in FIG. 6) of the outer tub 11 and the ultrasonic blocking. This is the point where the cylinder 61 is introduced.
The ultrasonic blocking cylinder 61 is a cylindrical body made of a plate material having a low ultrasonic propagation rate and formed smaller than the outer tank 11 and larger than the inner tank 14. An ultrasonic passage window 61a having a size close to the installation range of the ultrasonic transducer 12 on substantially one side surface is formed in a part thereof so as to penetrate inside and outside, and rotates around the inner tank 14 in the outer tank 11. Supported as possible. The rotation of the motor 51 is transmitted via the coupling 52 and the shaft 53.
[0048]
In this case, at the time of cleaning the wafer 20, the ultrasonic waves 12 a are simultaneously irradiated from the ultrasonic transducers 12, and at the same time, the ultrasonic blocking cylinder 61 is gently rotated. Then, as the ultrasonic blocking cylinder 61 rotates, the ultrasonic passage window 61a rotates around the inner tank 14, so that the ultrasonic wave 12a is inside and inside the ultrasonic blocking cylinder 61 only from the direction in which the ultrasonic passing window 61a comes. Since it propagates to the tank 14 etc., the irradiation direction of the ultrasonic wave seen from the wafer 20 changes continuously.
Thereby, this cleaning device 60 is provided in addition to the ultrasonic irradiation means 12 and rotates toward the object to be processed in the cleaning tank by rotating the strength of the irradiation intensity of the ultrasonic waves 12a in the cleaning tanks 11 and 14. The traveling direction of the ultrasonic wave or the irradiation direction is made a round.
When the ultrasonic blocking cylinder 61 is rotated once or more, all the fence-like residues are reliably removed also in this case.
[0049]
[Fifth embodiment]
A specific configuration of the fifth embodiment of the cleaning apparatus of the present invention will be described with reference to the drawings. FIG. 7 is a plan view schematically showing the basic structure.
[0050]
The cleaning device 70 of FIG. 7 differs from the cleaning device 60 of FIG. 6 in that the ultrasonic blocking cylinder 61 is omitted and the control method of each ultrasonic transducer 12 is changed instead.
In each of the ultrasonic transducers 12 installed in all directions, the output power of the ultrasonic wave is variably controlled periodically (for example, in a sine wave shape, a triangular wave shape, or a sawtooth shape). It is shifted by ゜.
[0051]
In this case, at the time of cleaning the wafer 20, the ultrasonic waves 12 a are irradiated from the respective ultrasonic transducers 12, but this is not performed all at once, but is performed while changing in strength so as to circulate in order. These combined vectors rotate while facing the inner tank 14.
Thereby, this cleaning device 70 is provided as a part of the ultrasonic irradiation means 12 and the cleaning tank is rotated by shifting the phase of the irradiation intensity of the ultrasonic waves 12a in the cleaning tanks 11 and 14 and rotating the traveling direction or the irradiation direction. The traveling direction or irradiation direction of the ultrasonic wave toward the object to be processed is made to make a round.
Also in this case, all the fence-like residues are reliably removed.
[0052]
[Sixth embodiment]
A specific configuration of the sixth embodiment of the cleaning apparatus of the present invention will be described with reference to the drawings. FIG. 8 is a front view of the main part schematically showing the basic structure.
This cleaning device 80 directly holds the workpieces that have been transported and cleans them one by one while rotating the upper surface while being immersed in a stripping solution.
[0053]
For this purpose, the cleaning device 80 includes a turntable 82 attached to the upper end of a shaft 81 that is rotationally driven by a motor or the like, and a block 83 that is provided in the immediate vicinity of the side peripheral surface and holds the ultrasonic transducer 12. And a nozzle 84 for releasing the stripping solution 15 with the tube tip directed on the turntable 82. Then, while the wafer 20 is vacuum chucked on the turntable 82 and gently rotated, the peeling liquid 15 is applied from the nozzle 84 to the upper surface of the wafer 20, that is, the main surface, and the ultrasonic vibrator 12 is also operated. Yes.
[0054]
In this case, when the stripping solution 15 spreads on the upper surface of the wafer 20 with the rotation, a part thereof reaches the block 83, and the ultrasonic wave 12 a is sent from the ultrasonic vibrator 12 there to the stripping solution 15. When viewed from the wafer 20, the ultrasonic waves 12 a having an oscillation frequency exceeding the resonance frequency with the stripping solution 15 are irradiated while changing the traveling direction.
In this way, the cleaning with the flowing stripping solution 15 is performed with a round of ultrasonic irradiation, and as a result, all the fence-like residues are also reliably removed in this case.
[0055]
The above mechanism is surrounded by an appropriate waterproof cover or the like and an appropriate reflux means is provided so that the stripping solution 15 does not leak out of the apparatus. When the supply of the stripping solution 15 and the ultrasonic wave 12a is stopped, IPA or pure water is applied from the nozzle 84 or from another nozzle, air is further blown, and the turntable 82 is rotated at a high speed to finish the cleaning. Drying is performed. Then, the cleaned wafer 20 is sent out from the turntable 82 by a transfer mechanism (not shown).
Thus, the wafers 20 are sequentially processed one by one.
[0056]
[Modification]
In the above embodiment, ashing is performed after etching and then cleaning is performed, but application of the present invention is not limited to the procedure. For example, even in a state where the resist remains on the pattern before ashing, the resist and the fence-like residue may be simultaneously removed by the above-described ultrasonic cleaning using an ultrasonic wave and a stripping solution. . In this case, since the fence-like residue is removed after the resist is dissolved, it is preferable to extend the cleaning time slightly. Even if the cleaning time is somewhat longer, performing the cleaning process without ashing also has the effect of removing the resist at the same time and omitting the ashing process, so the total processing time is often shortened.
[0057]
Moreover, the effect of peeling increases by heating a peeling liquid at 40 to 100 degreeC, and the cleaning time by an ultrasonic wave can be shortened.
Furthermore, in addition to resist masks, fence-like residues are also generated when silicon oxide or silicon nitride called hard masks are used as masks. In this case as well, removal of the residues can be achieved by applying the above cleaning method after removing the mask. Is possible.
The above technique is also effective for fence-like residues such as Cu and Cu alloys, which are high melting point metals and have low volatility like noble metals.
[0058]
In addition, the peeled fence-like residue is formed differently depending on the etching gas and its flow rate ratio, and many of them may not dissolve but remain as particles in the stripping solution, but the stripping solution is circulated through the filter. It is possible to prevent contamination by letting or discarding. In that case, a stripping solution supply / discharge tube, a pump and a filter connected to the stripping solution, and the like may be attached to the cleaning tank of the cleaning device.
[0059]
Further, in the cleaning device 40 of the second embodiment (see FIG. 4), the rotation of the wafer 20 is performed by rotationally driving the inner tub 14, but the inner tub 14 is fixed and has a net-like shape. The shelf body may be rotationally driven.
Further, in the cleaning device 80 of the sixth embodiment (see FIG. 8), the block 83 and the ultrasonic transducer 12 are installed on the opposite side of the nozzle 84, but these may be installed on the same side, and the ultrasonic wave The vibrator 12 may be incorporated not in the block 83 but in the nozzle 84 or its support part.
[0060]
【The invention's effect】
As is apparent from the above description, in the surface treatment method of the first solving means of the present invention, the ultrasonic wave is also irradiated when cleaning with the stripper performed after etching, so that the resist or the like At the same time, the fence-like residue is removed, and as a result, there is an advantageous effect that the side wall deposits can be removed without increasing the number of steps.
[0061]
Further, in the surface treatment method of the second solving means of the present invention, the fence-like residue is removed by making the ultrasonic stimulation fine vibration and taking the auxiliary action of the stripping solution into consideration. In addition, the surface of the object to be processed is not subjected to undesirably strong stimulation, and as a result, the side wall deposit can be removed without increasing the number of steps and without damaging the object to be processed. Play.
[0062]
Furthermore, in the cleaning device of the third solving means of the present invention, by combining the cleaning device with a specific ultrasonic irradiation means, fine vibration ultrasonic waves are also irradiated when cleaning with the stripping solution, Fence-like residues are removed together with resist without giving undesired strong stimulation to the surface of the object to be processed, and as a result, the side wall deposit can be removed without increasing the number of steps and without damaging the object to be processed. There is an advantageous effect of becoming.
[0063]
Further, in the cleaning apparatus of the fourth and fifth solving means of the present invention, the relative positional relationship between the object to be processed and the ultrasonic wave makes one round or one round, so that the fence-like residue Even if there is anisotropy in the rigidity, etc. of ultrasonic waves and the stimulation of ultrasonic waves, there is an advantageous effect that the side wall deposits can be reliably removed without increasing the number of processes and without damaging the workpiece. Play.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a basic structure of a cleaning apparatus according to a first embodiment of a surface treatment method and a cleaning apparatus of the present invention.
FIG. 2 is a schematic diagram relating to a metal etching process or the like in the surface treatment method, and shows a process of forming a fence-like residue.
FIG. 3 is a schematic diagram relating to a cleaning step in the surface treatment method, and shows a removal state of a fence-like residue by ultrasonic cleaning in a stripping solution.
FIG. 4 is a structural schematic diagram of a second embodiment of the cleaning apparatus of the present invention.
FIG. 5 is a schematic structural view of a third embodiment of the cleaning apparatus of the present invention.
FIG. 6 is a schematic structural diagram of a fourth embodiment of the cleaning apparatus of the present invention.
FIG. 7 is a schematic structural view of a fifth embodiment of the cleaning apparatus of the present invention.
FIG. 8 is a schematic structural view of a sixth embodiment of the cleaning apparatus of the present invention.
[Explanation of symbols]
10 Cleaning device
11 Outer tank (cleaning tank)
12 Ultrasonic transducer (ultrasonic transmitter, ultrasonic irradiation means)
12a ultrasound
13 Pure water (ultrasonic wave propagation body)
14 Inner tank (cleaning tank, means for holding stripping solution and workpiece, ultrasonic wave propagation body)
15 Stripper (ultrasonic wave propagation body, ultrasonic medium)
20 Wafer (semiconductor substrate, object to be cleaned after metal etching, object to be processed)
21 Silicon wafer (silicon substrate, substrate)
22 Oxide film (insulating film)
23 Titanium (noble metal, refractory metal, surface metal to be etched)
24 Platinum (noble metal, refractory metal, surface metal to be etched)
24a High density plasma (plasma for etching)
25 resist
25a Oxygen plasma (ashing plasma)
26 Fence-like residue (side wall deposit)
40 Cleaning device
41 motor (rotation drive means)
42 Coupling (rotation drive means)
43 Shaft (Rotary drive means)
50 Cleaning device
51 Motor (Ultrasonic vibrator circuit)
52 Coupling (Circuit of ultrasonic transducer)
53 Shaft (Measuring means of ultrasonic transducer)
54 Rotating rod (circular means for ultrasonic transducer)
60 Cleaning device
61 Ultrasonic blocker (partial suppression body, ultrasonic travel direction, etc.)
61a Ultrasonic passage window (partial propagation means, ultrasonic traveling direction, etc.)
70 Cleaning device
80 Cleaning device
81 Shaft (Rotary drive means)
82 Turntable (Workpiece holding means)
83 blocks (Ultrasonic vibrator holding means)
84 Nozzle (peeling solution immersion means)

Claims (4)

In a cleaning apparatus equipped with a means for immersing a plate-like object to be processed in a stripping solution for cleaning,
  An inner tank that horizontally supports the object to be processed immersed in an internal stripping solution;
  An outer tank capable of storing the inner tank;
  The oscillation frequency of the ultrasonic wave that is arranged in the outer tank and is irradiated toward the object to be processed is set to a value at which the fence-like residue formed on the surface of the object to be processed directly receives vibration energy. Ultrasonic irradiation means for irradiating ultrasonic waves in the horizontal direction;
  An inner tank rotating means for rotating the inner tank about a vertical axis;
  A cleaning apparatus comprising: In a cleaning apparatus equipped with a means for immersing a plate-like object to be processed in a stripping solution for cleaning,
  An inner tank that horizontally supports the object to be processed immersed in an internal stripping solution;
  An outer tank capable of storing the inner tank;
  The oscillation frequency of the ultrasonic wave that is arranged in the outer tank and is irradiated toward the object to be processed is set to a value at which the fence-like residue formed on the surface of the object to be processed directly receives vibration energy. Ultrasonic irradiation means for irradiating ultrasonic waves in the horizontal direction;
  An ultrasonic vibrator circuit for rotating the ultrasonic irradiation means around the inner tank while facing the direction of the inner tank;
  A cleaning apparatus comprising: In the cleaning apparatus having means for cleaning by immersion of the plate-like object to be processed stripping solution,
An inner tank that horizontally supports the object to be processed immersed in an internal stripping solution;
An outer tank capable of storing the inner tank;
A plurality of ultrasonic waves that are arranged on the inner surface of the outer tub and are irradiated toward the object to be processed have a value that allows the fence-like residue formed on the surface of the object to directly receive vibration energy. A plurality of ultrasonic irradiation means configured to irradiate ultrasonic waves in the horizontal direction ;
Cylindrical ultrasonic blocking cylinder means disposed between the plurality of ultrasonic irradiation means and the inner tank, and provided with an ultrasonic passage window on a part of the side surface;
Ultrasonic blocking cylinder rotating means for rotating the ultrasonic blocking cylinder means;
Cleaning apparatus characterized by comprising a. In a cleaning apparatus equipped with a means for immersing a plate-like object to be processed in a stripping solution for cleaning,
  An inner tank that horizontally supports the object to be processed immersed in an internal stripping solution;
  An outer tank capable of storing the inner tank;
  A plurality of ultrasonic waves that are arranged on the inner surface of the outer tub and are irradiated toward the object to be processed are values at which the fence-like residue formed on the surface of the object directly receives vibration energy. A plurality of ultrasonic irradiation means for irradiating ultrasonic waves in the horizontal direction,
  Control means for periodically and variably controlling the output energy of the ultrasonic waves from the plurality of ultrasonic irradiation means;
  A cleaning apparatus comprising:

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