JP2014067864A - Substrate cleaning apparatus and substrate cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate cleaning apparatus which uses ultrasonic waves and thereby effectively removes particles on a substrate surface, and to provide a substrate cleaning method.SOLUTION: A cleaning apparatus 100 includes: a processing container 1 where the interior may be hermetically sealed; a spin chuck 10 which is provided in the processing container 1 and holds a wafer W that is a workpiece; a gas introduction device 20 which introduces a gas having the adjusted concentration into the processing container 1; a gas concentration sensor 30 serving as a detector which detects the gas concentration in the processing container 1; and an ultrasonic wave generation apparatus 40 which generates ultrasonic waves and transmits the ultrasonic waves to a surface of the wafer W held by the spin chuck 10.

Description

  The present invention relates to a substrate cleaning apparatus and a substrate cleaning method for cleaning a substrate in a manufacturing process of, for example, a semiconductor device.

  In the manufacturing process of a semiconductor device or the like, a substrate such as a semiconductor wafer is cleaned. Conventionally, dip-type cleaning has been performed in which a plurality of substrates are immersed in a large immersion bath for cleaning, but in recent years, single-wafer type spin cleaning has become mainstream as the substrate size increases. There is (for example, Patent Document 1). Single-wafer spin cleaning can uniformly clean the surface of large-diameter substrates, reduces the reattachment of contaminants removed by cleaning, and reduces the amount of cleaning liquid and rinsing pure water used. There are advantages.

  Ultrasonic waves are widely used for spin cleaning substrate cleaning. This discharges the cleaning liquid from the ultrasonic nozzle onto the surface of the substrate while rotating the substrate in the cleaning chamber, and oscillates the ultrasonic vibrator built in the ultrasonic nozzle. Then, the ultrasonic wave is propagated to the substrate surface through the liquid film of the cleaning liquid, and the substrate surface is cleaned by using physical force such as collision of liquid due to vibration energy of the ultrasonic wave and centrifugal force. The cleaning liquid discharged onto the substrate surface moves outward in the radial direction of the substrate with particles separated by ultrasonic vibration due to the centrifugal force accompanying the rotation of the substrate, and flows out from the peripheral portion of the substrate into the cleaning chamber.

  By the way, in recent years, miniaturization of semiconductor devices has progressed, and there is a demand for cleaning a substrate on which a fine pattern is formed. However, when spin cleaning is performed on a substrate having a fine pattern, the sound pressure of the ultrasonic wave is too strong, and the pattern formed on the substrate surface may be destroyed. Similarly to the ultrasonic method, the two-fluid spray method that has been widely used in the past removes particles by generating fine droplets from the spray nozzle and causing them to collide with the substrate. It is difficult to remove. This is because the flow of water hardly occurs near the boundary between the substrate and water, and an effective force for removing particles cannot be given. In addition, the use of pure water causes problems such as material loss due to dissolution of the water-soluble material on the substrate surface, and the need for a large amount of isopropyl alcohol in the drying step after cleaning.

JP 2009-71272 A

  An object of the present invention is to provide a substrate cleaning apparatus and a substrate cleaning method capable of effectively removing particles on a substrate surface using ultrasonic waves.

  A substrate cleaning apparatus according to the present invention includes a processing container that accommodates a substrate, a substrate holding device that rotatably holds the substrate in the processing container, and a gas introduction device that introduces a concentration-adjusted gas into the processing container. And a detection device that detects a gas concentration in the processing container, and an ultrasonic generator that generates ultrasonic waves and propagates the ultrasonic waves to the surface of the substrate held by the substrate holding device. Then, the substrate cleaning apparatus of the present invention introduces the gas whose concentration is adjusted in the processing container by the gas introduction device, and generates the ultrasonic wave while adjusting the gas concentration in the processing container. The substrate is cleaned with ultrasonic waves.

  Moreover, the substrate cleaning apparatus of the present invention may further include a cooling device for cooling the substrate.

  In the substrate cleaning apparatus of the present invention, the gas introduction device may include a vaporization device that vaporizes a liquid and a flow rate adjusting device that supplies the vaporized gas into the processing container at a predetermined flow rate. .

  In the substrate cleaning apparatus of the present invention, the concentration-adjusted gas may be air containing moisture.

  The substrate cleaning apparatus of the present invention further includes a control unit that adjusts the concentration and / or flow rate of the gas introduced into the processing container by the gas introduction device based on the gas concentration detected by the detection device. It may be.

  The substrate cleaning method of the present invention cleans a substrate using ultrasonic waves generated by an ultrasonic generator, carries the substrate into a processing container, and rotatably holds the substrate by a substrate holding device. A step of introducing a concentration-adjusted gas into the processing container, adjusting a gas concentration in the processing container, and an ultrasonic generator while rotating the substrate held in the substrate holding device. And applying ultrasonic waves to the surface of the substrate and propagating the ultrasonic waves on the substrate surface to clean the substrate.

  The substrate cleaning method of the present invention may further include a step of cooling the substrate before the step of cleaning the substrate.

  Moreover, the substrate cleaning method of the present invention may perform a step of cleaning the substrate while cooling the substrate.

  In the substrate cleaning method of the present invention, the gas whose concentration is adjusted may be air containing moisture. In this case, it is desirable that the moisture concentration in the processing container is less than the saturated water vapor amount at the atmospheric temperature in the apparatus.

  According to the present invention, the gas whose concentration is adjusted by the gas introduction apparatus is introduced into the processing container, and the gas molecules are attached to the surface of the substrate in several layers by adjusting the gas concentration in the processing container. Ultrasonic cleaning can be performed in the state. Thereby, particles on the substrate surface can be effectively removed without causing pattern collapse or material loss due to ultrasonic waves.

It is a schematic block diagram of the washing | cleaning apparatus which concerns on one embodiment of this invention. It is a schematic diagram explaining the state change of the wafer surface which arises with the cleaning method of one embodiment of this invention, and has shown the state before cleaning. FIG. 4 is a schematic diagram for explaining a change in the state of the wafer surface caused by the cleaning method according to the embodiment of the present invention, and shows a state in which water molecules are attached to the surface of the wafer W; FIG. 5 is a schematic diagram for explaining a change in the state of the wafer surface caused by the cleaning method according to the embodiment of the present invention, and shows a state in which ultrasonic waves are propagated to the surface of the wafer W; It is a schematic diagram explaining the washing | cleaning method of a comparative example. It is a schematic diagram explaining another washing | cleaning method of a comparative example.

  Embodiments of the present invention will be described below with reference to the drawings.

[Outline of cleaning equipment]
First, a configuration example of a cleaning apparatus according to an embodiment of the present invention will be described. FIG. 1 is a longitudinal sectional view showing a schematic configuration of a cleaning apparatus 100 according to the present embodiment. The cleaning apparatus 100 is a processing container 1 capable of sealing the inside, and a substrate holding apparatus that is provided in the processing container 1 and holds a semiconductor wafer (hereinafter simply referred to as “wafer”) W that is an object to be processed. The spin chuck 10 is provided. The cleaning apparatus 100 includes a gas introduction device 20 that introduces a gas whose concentration is adjusted into the processing container 1, and a gas concentration sensor 30 as a detection device that detects the gas concentration in the processing container 1. . The cleaning apparatus 100 includes an ultrasonic generator 40 that generates ultrasonic waves and propagates the ultrasonic waves to the surface of the wafer W held by the spin chuck 10, and a cooling device 50 that cools the wafer W. Yes. Furthermore, the cleaning apparatus 100 includes a control unit 60 that controls each component in the cleaning apparatus 100.

  The cleaning apparatus 100 introduces a gas whose concentration is adjusted in the processing container 1 by the gas introduction apparatus 20, and adjusts the gas concentration in the processing container 1 while using the ultrasonic wave generated by the ultrasonic generator 40. W is washed.

(Processing container)
The processing container 1 includes a top plate 1a, a side wall 1b, and a bottom wall 1c. The processing container 1 is made of a material such as aluminum or SUS, for example. Although not shown, a loading / unloading port for the wafer W is formed on one side surface of the processing container 1, and an opening / closing shutter is provided at the loading / unloading port.

(Spin chuck)
As shown in FIG. 1, a spin chuck 10 is provided inside the processing container 1 as a rotation holding member that holds the wafer W by suction. The spin chuck 10 has a horizontal upper surface, and a suction port (not shown) for sucking, for example, the wafer W is provided on the upper surface. The wafer W can be sucked and held on the spin chuck 10 by suction from the suction port.

  The spin chuck 10 includes a column 10 a and a drive unit 11. The drive unit 11 has a rotation drive unit such as a motor, and can rotate the wafer W held by the spin chuck 10 in a horizontal direction at a predetermined speed by rotating the support column 10a. Moreover, the drive part 11 has a raising / lowering drive part, such as a cylinder, for example, and can move the spin chuck 10 containing the support | pillar 10a up and down up and down.

  A guide ring 12 is provided on the lower side of the spin chuck 10, and the outer peripheral edge of the guide ring 12 is bent downward and extends. A cup 13 is provided outside the spin chuck 10, the wafer W held by the spin chuck 10, and the guide ring 12 so as to surround the spin chuck 10. The cup 13 can receive and collect particles scattered or dropped from the wafer W.

  An opening 13 a larger than the wafer W is formed at the top of the cup 13 so that the spin chuck 10 can be moved up and down. Further, a gap 14 serving as a discharge path is formed between the inner peripheral surface of the cup 13 and the bent outer peripheral edge of the guide ring 12. The lower side of the cup 13 forms a gas-liquid separation part by forming a curved path together with the outer peripheral edge portion of the guide ring 12. An exhaust port 15 for exhausting the atmosphere in the cup 13 is formed in the inner region of the bottom of the cup 13, and an exhaust pipe 15 a is connected to the exhaust port 15. Further, a drain port 16 for discharging the collected liquid is formed in the outer region of the bottom portion of the cup 13, and a drain tube 16 a is connected to the drain port 16.

(Gas introduction device)
The gas introduction device 20 introduces a gas whose concentration is adjusted into the processing container 1. The gas introduction device 20 includes a carrier gas source 21, a vaporizer 22 that vaporizes a liquid while introducing the carrier gas from the carrier gas source 21, and a pipe 23 that connects the carrier gas source 21 and the vaporizer 22. And a valve 24 provided in the pipe 23. The gas introduction device 20 includes a pipe 25 that supplies the gas vaporized by the vaporizer 22 into the processing container 1 and a flow rate adjusting device (mass flow controller (MFC)) that is provided in the pipe 25 and adjusts the flow rate of the supplied gas. ) 26 and a valve 27 provided in the pipe 25. Further, the gas introduction device 20 is connected to a gas introduction port 28 provided on the side wall 1 b of the processing container 1 by a pipe 25. Note that the cleaning apparatus 100 may include, for example, a purge gas introduction apparatus for purging the inside of the processing container 1 as a gas introduction mechanism other than the gas introduction apparatus 20. Examples of the gas introduced into the processing container 1 by the gas introduction device 20 include organic solvents such as air containing moisture, nitrogen gas containing moisture, and methanol.

  By introducing the gas whose concentration is adjusted into the processing container 1 by the gas introducing device 20, the gas concentration in the processing container 1 can be strictly managed. Further, the gas concentration in the processing container 1 can be detected by a gas concentration sensor 30 mounted so as to be exposed to the internal atmosphere via the side wall 1 b of the processing container 1. For example, when the gas introduced into the processing container 1 by the gas introducing device 20 is air containing moisture or nitrogen gas containing moisture, a hygrometer is used as the gas concentration sensor 30.

(Ultrasonic generator)
The ultrasonic generator 40 generates an ultrasonic wave, applies the ultrasonic wave to the surface of the wafer W held by the spin chuck 10, and propagates it. The ultrasonic generator 40 includes an ultrasonic wave application head 41 including a vibrator (not shown), an arm member 42 that holds the ultrasonic wave application head 41, a head drive unit 43 that moves the ultrasonic wave application head 41, and an ultrasonic wave And an ultrasonic oscillator 44 that outputs a pulse signal toward the applying head 41. The head drive unit 43 moves the ultrasonic wave application head 41 relative to the wafer W while keeping the distance between the ultrasonic wave application head 41 and the surface of the wafer W constant. The ultrasonic oscillator 44 outputs a pulse signal to the vibrator (not shown) of the ultrasonic wave applying head 41 based on the control signal from the control unit 60. Thereby, the vibrator vibrates ultrasonically, and the ultrasonic vibration is applied to the surface of the wafer W. In this embodiment, since the ultrasonic wave application head 41 is used in a gas phase, it is preferable to use an ultrasonic wave application head 41 having an amplification facility (for example, a horn) or a heat propagation type vibrator.

(Cooling system)
The cooling device 50 includes nozzles 51A and 51B, a refrigerant source 52 that supplies refrigerant to the nozzles 51A and 51B, and refrigerant supply pipes 53A and 53B that connect the nozzles 51A and 51B and the refrigerant source 52. The nozzle 51 </ b> A is arranged so that the coolant can be supplied to the back surface of the peripheral edge of the wafer W. The nozzle 51B is arranged so that the coolant can be supplied toward the back surface of the central portion of the wafer W through the coolant supply pipe 53B inserted into the support column 10a. The cooling device 50 can cool the wafer W by supplying the coolant cooled to a predetermined temperature from the coolant source 52 and spraying the coolant onto the back surface of the wafer W from the nozzles 51A and 51B. Here, as the refrigerant, for example, He gas, CO ₂ gas, or the like can be used. The wafer W may be cooled by, for example, a chiller mechanism.

(Control part)
Each end device (for example, the spin chuck 10, the gas introduction device 20, the gas concentration sensor 30, the ultrasonic generator 40, the cooling device 50, etc.) constituting the cleaning device 100 is connected to the control unit 60 and controlled. It has become. The control unit 60 having a computer function includes a controller 61 having a CPU, a user interface 62 and a storage unit 63 connected to the controller 61. The user interface 62 includes a keyboard and a touch panel on which a process manager manages command input to manage the cleaning apparatus 100, a display that visualizes and displays the operating status of the cleaning apparatus 100, and the like. The storage unit 63 stores a recipe in which a control program (software) for realizing various processes executed by the cleaning apparatus 100 under the control of the controller 61 and processing condition data are recorded. Then, if necessary, an arbitrary control program or recipe is called from the storage unit 63 by an instruction from the user interface 62 and is executed by the controller 61, so that the processing container of the cleaning apparatus 100 is controlled under the control of the controller 61. A desired cleaning process is performed within 1.

  Specifically, the controller 61 instructs each end device to operate or stop under the conditions defined in the recipe. For example, the controller 61 sends a control signal to the gas introduction device 20 in order to keep the gas concentration in the processing container 1 within a range based on the recipe, and instructs the operation and stop, as well as the gas introduced into the processing container 1. Adjust the flow rate and concentration. In this case, the controller 61 can also perform feedback control on the gas supply device 20 with reference to the signal of the detected value of the gas concentration in the processing container 1 detected by the gas concentration sensor 30. The controller 61 also sends a control signal to the spin chuck 10, the ultrasonic generator 40, the cooling device 50, etc. to instruct operation and stop, and the processing container 1 detected by the gas concentration sensor 30. Feedback control can be performed on these end devices while referring to the signal of the detected value of the gas concentration. For example, the controller 61 can adjust the oscillation frequency or vibration amplitude of the ultrasonic wave generated by the ultrasonic generator 40 according to the detected value of the gas concentration in the processing container 1 detected by the gas concentration sensor 30. it can. The controller 61 can also send a control signal to the drive unit 11 to adjust the rotation speed of the spin chuck 10 in accordance with the detected value of the gas concentration in the processing container 1 detected by the gas concentration sensor 30. . Furthermore, the controller 61 adjusts the cooling temperature of the wafer W by the cooling device 50 in accordance with the detected value of the gas concentration in the processing container 1 detected by the gas concentration sensor 30, so that the temperature of the refrigerant, the injection amount, etc. It can also be adjusted.

  Recipes such as the control program and processing condition data can be used by installing the recipe stored in the computer-readable recording medium 64 in the storage unit 63. The computer-readable recording medium 64 is not particularly limited, and for example, a CD-ROM, a hard disk, a flexible disk, a flash memory, a DVD, or the like can be used. Further, the recipe can be transmitted from other devices as needed via, for example, a dedicated line and used online.

[Cleaning method]
In the cleaning apparatus 100, a cleaning process using the ultrasonic waves generated by the ultrasonic generator 40 is performed on the wafer W. The cleaning process in the cleaning apparatus 100 includes, for example, a process of loading the wafer W into the processing container 1 and holding the wafer W rotatably by the spin chuck 10, introducing a gas into the processing container 1, and a gas concentration in the processing container 1. The wafer W is cleaned by rotating the wafer W while generating the ultrasonic wave by the ultrasonic generator 40 and propagating the ultrasonic wave to the surface of the wafer W held by the spin chuck 10. And a process. Hereinafter, each step will be described.

(Wafer loading and fixing)
First, the wafer W is loaded by an external transfer device with the loading / unloading port (not shown) of the processing container 1 opened. The spin chuck 10 is configured to be moved up and down by the drive unit 11 as described above, and transfers the wafer W to and from the transfer device at the raised position. Next, the wafer W is lowered while being held on the spin chuck 10 and set at the cleaning position.

(Adjustment of gas concentration)
Next, a gas having a predetermined concentration is introduced into the processing container 1 by the gas introduction device 20. That is, the valve 24 of the pipe 23 and the valve 27 of the pipe 25 are opened, and the carrier gas is introduced into the vaporizer 22 from the carrier gas source 21. The gas vaporized by the vaporizer 22 is supplied into the processing container 1 through the gas inlet 28 while the flow rate of the gas is adjusted by the mass flow controller 26. As carrier gas, dry air, dry nitrogen gas, etc. can be used, for example. Further, examples of the liquid stored in the vaporizer 22 and to be vaporized include distilled water and organic solvents.

  After the start of gas introduction, the gas concentration in the processing container 1 is stabilized by continuing to supply the gas for 10 to 300 seconds, for example. For example, when air containing moisture or nitrogen gas containing moisture is used as the gas, from the viewpoint of attaching an appropriate amount of water molecules to the surface of the wafer W, the humidity in the processing vessel 1 is, for example, 0.1% to the processing vessel. It is preferable to adjust so that it may become less than the saturated water vapor amount in the atmospheric temperature within 1. If the humidity in the processing container 1 is less than 0.1%, it is difficult to attach water molecules to the surface of the wafer W with high efficiency. If the humidity is higher than the saturated water vapor amount, excessive amounts of water molecules adhere to the surface of the wafer W. As a result, a liquid film is formed. In the present embodiment, no special control is required for the pressure in the processing container 1, and atmospheric pressure is preferable.

(Ultrasonic cleaning process)
Next, the driving unit 11 is driven to generate ultrasonic waves by the ultrasonic generator 40 while rotating the wafer W held by the spin chuck 10 at a predetermined speed, and the surface of the wafer W held by the spin chuck 10 is generated. The wafer W is cleaned by propagating ultrasonic waves. Specifically, a pulse signal is output from the ultrasonic oscillator 44 toward the ultrasonic wave application head 41 to apply ultrasonic vibration to the surface of the wafer W. During this time, the arm member 42 is moved by the head drive unit 43, and the ultrasonic wave application head 41 is scanned in the radial direction of the rotating wafer W.

In the ultrasonic cleaning process, the vibration frequency of the ultrasonic wave applied from the ultrasonic wave applying head 41 to the surface of the wafer W is preferably set so that the sound pressure on the surface of the wafer W is in the range of 1 × 10 ⁴ Pa to 1 × 10 ⁶ Pa. From the viewpoint of controlling, for example, it is preferable to be within a range of 20 kHz to 1.6 MHz.

  In addition, the rotational speed of the wafer W is preferably set within a range of 100 to 1000 rpm, for example, from the viewpoint of efficiently scattering particles peeled off by ultrasonic waves outwardly of the wafer W by centrifugal force.

  Here, in the cleaning method of the present embodiment, the significance of performing the ultrasonic cleaning process while controlling the gas concentration in the processing container 1 using the gas introducing device 20 will be described with reference to FIGS. 2 to 4 are schematic diagrams for explaining a change in the state of the surface of the wafer W caused by the cleaning method of the present embodiment. Here, a case where air containing a predetermined concentration of water is introduced into the processing container 1 will be described as an example. 5A and 5B are schematic views for explaining the surface state of the wafer W in the cleaning method of the comparative example.

  FIG. 2 shows a state before cleaning. In this state, the humidity in the processing container 1 is not adjusted. A plurality of fine particles 101 are attached to the surface of the wafer W. Next, FIG. 3 shows a state in which water molecules 102 are attached to the surface of the wafer W. This state is such that several layers, for example, 5 layers or less, preferably about 2 to 3 molecular layers of water molecules 102 adhere to the surface of the wafer W, and a liquid film is formed (completely wet state). ) Is different. The amount of adhesion is indistinguishable from the dry state by visual inspection. As described above, when several layers of water molecules 102 adhere to the surface of the wafer W, air containing a predetermined concentration of moisture is introduced into the processing container 1 by the gas introduction device 20, and the humidity in the processing container 1 is set to the above-described humidity. Can be produced by controlling within range.

  Next, as shown in FIG. 4, an ultrasonic wave U is generated by the ultrasonic wave generator 40, and the ultrasonic wave is propagated from the ultrasonic wave application head 41 to the surface of the wafer W held on the spin chuck 10. In this embodiment, by propagating the ultrasonic wave U through several layers of water molecules 102, as shown in FIG. 4, the particles 101 existing on the surface of the wafer W are effectively removed by physical force due to ultrasonic vibration. And can be removed from the surface of the wafer W. The particles 101 scattered or dropped from the wafer W by the centrifugal force of rotation are received by the cup 13 and fall to the bottom of the cup 13 through the gap 14. The dropped particles can be collected from the drain 16 by washing the inside of the cup 13 with water or the like.

  The ultrasonic cleaning time is not particularly limited, but can be, for example, in the range of 1 to 10 minutes.

(Wafer unloading)
When the ultrasonic cleaning for a predetermined time is completed, the rotation of the ultrasonic generator 40 and the spin chuck 10 is stopped, and the wafer W is moved up to the delivery position together with the spin chuck 10. Then, by using an external transfer device, the wafer W is unloaded from the processing container 1 in the reverse procedure to the above, whereby the cleaning process for one wafer W is completed.

(Optional process)
The cleaning method of the present embodiment can include arbitrary steps other than those described above. For example, it is preferable to provide a step of cooling the wafer W before the step of cleaning the wafer W. The cooling of the wafer W can be performed by supplying a coolant, for example, He gas cooled to a predetermined temperature, from the coolant source 52 of the cooling device 50 and injecting it from the nozzle 51A and / or the nozzle 51B to the back surface of the wafer W. . The temperature of the wafer W at the time of ultrasonic cleaning may be in the range of 0 ° C. to 200 ° C., for example, but when the wafer W is cooled in this step, it is about 10 ° C. lower than the ambient temperature in the processing chamber 1. It is preferable to cool within the range up to the temperature. Thus, by cooling the wafer W to a temperature lower than the atmospheric temperature in the processing container 1, molecules (for example, water molecules) contained in the gas are likely to adhere to the surface of the wafer W, and several layers are formed. Gas molecules having a thickness can be efficiently formed on the surface of the wafer W. Further, it is preferable that the cooling of the wafer W is continuously performed by the cooling device 50 while the ultrasonic wave is applied to the wafer W by the ultrasonic generator 40.

[Action]
Next, the effects of the present invention will be described in comparison with the cleaning method of the comparative example. FIG. 5A shows a case where ultrasonic cleaning is performed in a state where a large amount of water 200 exists on the surface of the wafer W. For example, a dip method in which the wafer W is immersed in water or a wafer W fixed to the spin chuck 10 is used. An example is a spin cleaning method in which ultrasonic waves U are applied while a liquid film having a thickness of about several millimeters is formed while water 200 is dropped on the surface. FIG. 5B shows a dry cleaning method in which ultrasonic cleaning is performed in a state where the surface of the wafer W is completely dried.

As shown in FIG. 5A, in a method of propagating ultrasonic vibrations in water (hereinafter sometimes referred to as “wet cleaning method”), the sound pressure on the surface of the wafer W is, for example, 1 as an ultrasonic generator. because × ones can be used as a ¹⁰ 5 to 5 × ¹⁰ about 5 Pa size, the removal efficiency of particles 101 is higher by a large physical force. As an example of such an ultrasonic generator, a quartz vibrator washing machine (model W-357-1MQB-CV) manufactured by Honda Electronics Co., Ltd. can be cited. However, as described above, the wet cleaning method greatly damages the pattern formed on the surface of the wafer W, and material loss due to elution of the water-soluble material becomes a problem.

On the other hand, in the case of the dry cleaning method as shown in FIG. 5B, an ultrasonic generator having an amplification facility (horn) in the subsequent stage of the vibrator or a device having a heat propagation vibrator is used. . In this case, since the sound pressure on the surface of the wafer W remains at, for example, about 2 × 10 ² Pa, there is a problem that the removal efficiency of the particles 101 cannot be sufficiently obtained. In addition, the ultrasonic generator (for example, the quartz vibrator type washing machine (model W-357-1 MQB-CV) manufactured by Honda Electronics Co., Ltd.) used in the wet cleaning method can generate a large sound pressure in the air. However, the vibrator is abnormally heated and cannot be used in the dry cleaning method.

The magnitude of the sound pressure generated by the ultrasonic vibration depends on the molecular density on the surface of the wafer W. In contrast to the cleaning method of the comparative example shown in FIGS. 5A and 5B, in the cleaning method of the present embodiment, as shown in FIG. 4, the ultrasonic wave U is propagated through several layers of water molecules 102. The sound pressure applied to the particles 101 can be increased to, for example, about 1 × 10 ⁶ Pa at the maximum. That is, by adhering several layers of water molecules 102 to the surface of the wafer W, an ultrasonic generator that is normally used in the dry cleaning method is used to generate a larger sound pressure than in the dry cleaning method. It becomes possible to add to. Moreover, if the sound pressure is at this level, the problem of damage to the pattern as in the wet method does not occur, and the amount of moisture is small, so that no material loss occurs. Based on such a principle, in the cleaning method of the present embodiment, the particles 101 existing on the surface of the wafer W can be effectively peeled and efficiently removed from the surface of the wafer W.

  Note that the thickness (number of layers N) of the water molecule layer adhered to the surface of the wafer W by adjusting the humidity in the processing container 1 can be measured by the following procedure. First, the entire weight is measured with water molecules attached to the surface of the wafer W. Next, the weight of the wafer W is measured in a state where the attached moisture is heated and desorbed. Then, the weight of the adhering moisture is calculated from the change in the weight of the wafer W before and after the water molecules are heated and desorbed. Next, assuming that one layer of water molecules is regularly arranged on the surface of the wafer W, the molecular weight M at that time is obtained by calculation. Further, the molecular weight M1 is obtained by calculation from the measured weight of the adhered water. Then, the thickness (number N of layers) of the water molecule layer attached to the surface of the wafer W can be calculated by the following formula: N = M1 / M.

  As described above, according to the cleaning apparatus 100 and the cleaning method of the present embodiment, the gas whose concentration is adjusted in the processing container 1 by the gas introduction device 20 is introduced, and the gas concentration in the processing container 1 is adjusted. Thus, ultrasonic cleaning can be performed in a state where several layers of gas molecules are attached to the surface of the wafer W. Thereby, particles on the surface of the wafer W can be effectively removed without causing pattern collapse or material loss due to ultrasonic waves.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment, A various deformation | transformation is possible. For example, the present invention is not limited to a case where a semiconductor wafer is used as an object to be processed, and can be applied to a case where, for example, a solar cell panel substrate or a flat panel display substrate is used as an object to be processed.

  Further, the gas introduction device 20 is not limited to the bubbling vaporizer 22 having the configuration shown in FIG. 1 but may be, for example, a vaporization method by jetting from a nozzle or the like, as long as it can generate a gas having a predetermined concentration.

  DESCRIPTION OF SYMBOLS 1 ... Processing container, 10 ... Spin chuck, 11 ... Drive part, 12 ... Guide ring, 13 ... Cup, 15 ... Exhaust port, 16 ... Drain port, 20 ... Gas introduction apparatus, 21 ... Carrier gas source, 22 ... Vaporization 30 ... Gas concentration sensor, 40 ... Ultrasonic generator, 41 ... Ultrasonic application head, 44 ... Ultrasonic oscillator, 50 ... Cooling device, 60 ... Controller, 61 ... Controller, 62 ... User interface, 63 ... Memory 64, recording medium, 100, cleaning device, W, semiconductor wafer (wafer)

Claims (10)

A processing container for containing a substrate;
A substrate holding device for rotatably holding the substrate in the processing container;
A gas introduction device for introducing a concentration-adjusted gas into the processing container;
A detection device for detecting a gas concentration in the processing container;
An ultrasonic generator that generates ultrasonic waves and propagates the ultrasonic waves to the surface of the substrate held by the substrate holding device;
A gas whose concentration is adjusted by the gas introduction device is introduced into the processing vessel, and the substrate is cleaned by the ultrasonic wave generated by the ultrasonic generator while adjusting the gas concentration in the processing vessel. Substrate cleaning device to perform.   The substrate cleaning apparatus according to claim 1, further comprising a cooling device that cools the substrate.   The substrate cleaning apparatus according to claim 1, wherein the gas introduction device includes a vaporization device that vaporizes a liquid and a flow rate adjusting device that supplies the vaporized gas into the processing container at a predetermined flow rate.   The substrate cleaning apparatus according to claim 1, wherein the concentration-adjusted gas is air containing moisture.   Furthermore, based on the gas concentration detected by the said detection apparatus, the control part which adjusts the density | concentration and / or flow volume of the gas introduce | transduced in the said processing container by the said gas introduction apparatus is provided. The substrate cleaning apparatus according to the item. A substrate cleaning method for cleaning a substrate using ultrasonic waves generated by an ultrasonic generator,
Carrying the substrate into the processing container and holding the substrate rotatably by the substrate holding device;
Introducing a gas whose concentration is adjusted in the processing container, and adjusting the gas concentration in the processing container;
Applying the ultrasonic wave generated by the ultrasonic generator to the surface of the substrate while rotating the substrate held by the substrate holding device, and cleaning the substrate by propagating the ultrasonic wave on the substrate surface;
A substrate cleaning method comprising:   The substrate cleaning method according to claim 6, further comprising a step of cooling the substrate before the step of cleaning the substrate.   The substrate cleaning method according to claim 7, wherein a step of cleaning the substrate is performed while cooling the substrate.   The substrate cleaning method according to claim 6, wherein the concentration-adjusted gas is air containing moisture.   The substrate cleaning method according to claim 9, wherein the humidity in the processing container is less than a saturated water vapor amount at the temperature of the atmosphere in the processing container.

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