JP2005093873A - Substrate treating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multipurpose substrate treating device that can exhibit the cleaning effect corresponding to a new material or manufacturing process introduced to a semiconductor device and, in addition, can cope with the need for cleaning technique which is expected to increasingly rise in future as the scale down and high integration of the semiconductor device advance. <P>SOLUTION: The substrate treating device is provided with a treating liquid supplying source 27 which supplies a treating liquid 2 onto a substrate W, a micro-bubble generator 28 which generates micro-bubbles in the treating liquid 2, and an ultrasonic vibrator 20 which emits an ultrasonic wave to the treating liquid 2 containing the micro-bubbles. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a substrate processing apparatus that removes metal, organic matter, particles and the like adhering to the surface of a substrate using microbubbles and ultrasonic waves.

  In the manufacturing process of semiconductor devices, a high degree of cleanliness is required, and cleaning techniques for removing dirt on a submicron basis are becoming increasingly important. In particular, with the progress of miniaturization and high integration of semiconductor devices, it is desired to realize a new cleaning technology corresponding to new materials and manufacturing processes being introduced into semiconductor devices.

New materials that are being introduced into semiconductor devices include metals such as Cu, Ru, Co, and Pt. Of these, Cu (copper) is likely to cause metal contamination, so that it is necessary to completely remove excess Cu remaining on the substrate. Cu is difficult to remove by the conventional RCA cleaning method, and is generally removed by using an HF processing solution. In addition, the cleaning method using ozone water (O ₃ ) can remove most metals, but cannot completely remove Cu.

  In recent years, with further miniaturization of semiconductor devices, there is a tendency to use a low-k material as an insulating film. With the introduction of this low-k material, removal of organic substances such as polymers and etching residues after etching the low-k material, and the inside of fine contact holes (wiring holes) formed in the low-k material A new cleaning technique that enables cleaning is desired. Since the hole diameter of a fine contact hole is extremely small, there has been a problem that cleaning defects are likely to occur inside the contact hole. In addition to this, it is further difficult to clean the contact hole due to further miniaturization of the contact hole diameter and the water repellency of the low-k material.

In addition, the ashing process using O ₂ plasma or the like damages the low-k material after the formation of the wiring hole, so that a resist stripping process using a new wet method is required instead. Furthermore, with the introduction of new materials and the miniaturization of semiconductor devices, the semiconductor device manufacturing process itself is changing. For this reason, realization of a new cleaning technique corresponding to a change in the manufacturing process is required. For example, with the introduction of new resist materials and changes in the etching process, the adhesion strength of polymers and resist residues to the underlayer such as insulating films may become higher than before, and these can be removed with conventional cleaning techniques. Is considered difficult. Furthermore, even in the cleaning around the gate in the previous process, it is expected that the removal performance of metal, organic matter and particles and the prevention of re-adhesion after removal will become increasingly severe due to the miniaturization and adoption of new materials.

  The present invention has been made in view of the above circumstances, can provide a cleaning effect corresponding to new materials and manufacturing processes introduced into semiconductor devices, and further advances in miniaturization and high integration of semiconductor devices. Accordingly, it is an object of the present invention to provide a multi-purpose substrate processing apparatus that can meet the needs for cleaning technologies that are expected to increase in the future.

In order to achieve the above-described object, the present invention provides a processing liquid supply source that supplies a processing liquid onto a substrate, a microbubble generator that generates microbubbles in the processing liquid, and a processing liquid that includes microbubbles. A substrate processing apparatus comprising an ultrasonic transducer for irradiating ultrasonic waves.
In a preferred aspect of the present invention, the microbubble has a diameter of 20 μm or less and an internal pressure of atmospheric pressure or more.

In a preferred aspect of the present invention, the microbubble generator is any one of a two-fluid nozzle, a gas disperser, a gas-liquid stirrer, and an electrolytic gas generator.
One preferable aspect of the present invention further includes a substrate holding unit that holds the substrate and a rotation mechanism that rotates the substrate holding unit, and the ultrasonic transducer faces the substrate held by the substrate holding unit. It is characterized by being arranged in.
In a preferred aspect of the present invention, the ultrasonic transducer has a treatment liquid inlet, and the treatment liquid is formed between the substrate held by the substrate holder and the ultrasonic transducer via the treatment liquid introduction port. It is supplied between.
In a preferred aspect of the present invention, the frequency of the ultrasonic wave emitted from the ultrasonic transducer is 5 to 100 MHz.

In the substrate processing apparatus according to the present invention, the microbubbles generated by the microbubble generator are irradiated with ultrasonic waves instead of generating microbubbles using cavitation caused by ultrasonic irradiation. According to the present invention having such a configuration, the cleaning effect inherent to the microbubbles can be further enhanced by irradiating the treatment liquid containing the microbubbles with ultrasonic waves. In addition, due to the synergistic effect of microbubbles and ultrasonic irradiation, various objects to be processed such as particles, metals, and organic substances can be removed from the substrate with high efficiency.
The principle of processing (cleaning) a substrate by the substrate processing apparatus according to the present invention will be described below.

Bubbles having a diameter of 20 μm or less, particularly 1 to 10 μm, exhibit the following characteristics.
(1) The coalescence of bubbles does not occur, the bubbles remain independent in the liquid for a long time and hardly disappear.
(2) Since the rising speed of the bubbles is extremely slow, it is excellent in diffusibility in the horizontal direction, and the bubbles are easily distributed uniformly in the liquid.
(3) In addition to staying in the liquid for a long time, the number of bubbles (bubble content rate) contained in the liquid per unit volume increases, and the surface area of the bubbles contained in the liquid per unit volume increases. If the bubbles are further miniaturized, the bubble content is further increased.
(4) Since the bubbles are charged, they have adsorptivity to suspended matters in the liquid.
(5) Depending on the surface tension of the bubble, the ultrasonic wave is reflected on the surface of the bubble.

In order to effectively use minute bubbles (hereinafter referred to as microbubbles) having such characteristics for the substrate cleaning process, in the present invention, ultrasonic waves are intermittently applied to the microbubbles in the processing liquid. The following effects can be obtained by irradiating the microbubbles with ultrasonic waves.
(I) When the microbubbles are irradiated with ultrasonic waves, the microbubbles are destroyed and a microjet flow is generated in the processing liquid. Using the energy of the microjet flow, particles attached to the substrate can be removed. In addition, when the microbubbles are destroyed, the gas that forms the microbubbles dissolves in a high concentration in the processing solution, and thus, by using the chemical properties of the gas, metals and organic substances that adhere to the substrate, etc. Can be removed.
(Ii) When the surface tension of the microbubble is strong, the bubble is not destroyed and the microbubble is agitated by ultrasonic waves. Therefore, the microbubbles can be diffused widely in the processing liquid, and particles and the like can be adsorbed on the surface of the microbubbles.
(Iii) Ultrasonic waves are irregularly reflected on the surface of the microbubble, so that it is possible to irradiate the ultrasonic wave to the finely processed portion such as a contact hole formed on the surface of the substrate, and the particles adhering to the finely processed portion. Etc. can be removed.
(Iv) Microbubbles generated by the cavitation phenomenon caused by ultrasonic irradiation are likely to damage the device due to the impact at the time of destruction. However, since the present invention does not generate microbubbles by ultrasonic energy, the ultrasonic frequency is reduced. It is possible to set the area where there is no device damage.

  According to the present invention, combined with the cleaning effect of microbubbles and the cleaning effect of ultrasonic waves, various objects to be processed such as particles, metals and organic substances can be removed from the substrate with high efficiency.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing the overall configuration of a substrate processing apparatus according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing a substrate processing apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the substrate processing apparatus includes a substrate holding unit 3 that holds a semiconductor wafer (substrate) W, a rotating shaft 4 that is fixed to the lower part of the substrate holding unit 3, and a lower part of the substrate holding unit 3. And an arranged container 5.

  The substrate holding unit 3 includes a circular substrate holding table 6 and a plurality of support pins 7 provided on the upper surface of the substrate holding table 6. The support pins 7 are arranged at equal intervals along the circumferential direction of the substrate holding table 6, and the peripheral edge of the semiconductor wafer W is supported by these support pins 7. Note that the semiconductor wafer W can be held by using a holding mechanism such as a vacuum chuck or an electrostatic chuck instead of the support pins 7.

  The rotating shaft 4 is rotatably supported by a bearing (not shown). A motor 8 is connected to the lower end of the rotating shaft 4 via a power transmission mechanism 17. With such a configuration, by driving the motor 8, the semiconductor wafer W held on the substrate support portion 3 is rotated via the rotation shaft 4. The motor 8 constitutes a rotation mechanism that rotates the substrate holding unit 3 and the semiconductor wafer W.

  The substrate processing apparatus according to this embodiment includes an arm 11 that can move up and down and can swing on a horizontal plane, and a head 12 that is fixed to a free end of the arm 11 via a support shaft 15. . The head 12 is disposed so as to face the semiconductor wafer W held by the substrate holding unit 3. A motor 14 is connected to the shaft portion 11a of the arm 11 via a power transmission mechanism 13, and the head 12 swings along the arrow A direction shown in FIG.

  An air cylinder 16 is connected to the lower end of the shaft 11 a of the arm 11. The air cylinder 16 is connected to a compressed air source (not shown), and the air cylinder 16 is driven by the compressed air supplied from the compressed air source. Therefore, the head 12 moves up and down by the air cylinder 16 via the shaft portion 11 a and the arm 11. The head 12 can be lowered to a position where the distance between the semiconductor wafer W held by the substrate holder 3 and the lower end of the head 12 is about 1 mm.

  The head 12 has a circular horizontal cross section, and the diameter thereof is substantially the same as that of the semiconductor wafer W. The head 12 has an ultrasonic transducer 20 attached to the lower surface thereof. Similar to the head 12, the ultrasonic transducer 20 has a circular horizontal cross section and is disposed so as to face the semiconductor wafer W held by the substrate holding unit 3. A power source (not shown) is connected to the ultrasonic transducer 20, and a high-frequency AC voltage is applied to the ultrasonic transducer 20 from this power source. The ultrasonic transducer 20 converts a periodic electrical signal supplied from a power source into mechanical vibration, thereby generating ultrasonic vibration. As the ultrasonic transducer 20, an electrostrictive transducer represented by barium titanate or lead zirconate titanate, or a magnetostrictive transducer represented by ferrite is preferably used.

  A processing liquid inlet 23 for introducing the processing liquid into the semiconductor wafer W is formed at the center of the head 12. The treatment liquid inlet 23 is open at the center of the ultrasonic transducer 20. The treatment liquid introduction port 23 communicates with a support hole 15 provided in the support shaft 15 and the arm 11, and the communication hole 25 communicates with a treatment liquid supply source 27 that stores the treatment liquid 2 via a pipe 26. . With such a configuration, the processing liquid 2 stored in the processing liquid supply source 27 is supplied onto the semiconductor wafer W from the processing liquid inlet 23 via the pipe 26 and the through hole 25.

  Inside the processing liquid supply source 27, a microbubble generator 28 that generates microbubbles in the processing liquid 2 is accommodated. The microbubble generator 28 is configured to generate microbubbles having a diameter of 20 μm or less, preferably 1 to 10 μm, and having an internal pressure equal to or higher than atmospheric pressure. Specific examples of the microbubble generator 28 include the following.

(1) Two-fluid nozzle The two-fluid nozzle has a liquid introduction hole opened in the mixing chamber and a gas introduction hole adjacent to the liquid introduction hole. A pressurized liquid (treatment liquid) is vigorously ejected from the liquid introduction hole into the mixing chamber, and the gas is sucked from the gas introduction hole by the negative pressure generated from the fluid energy of the injected liquid. Then, gas is mixed with the liquid flow to form a gas-liquid mixed flow containing microbubbles.
(2) Gas Disperser Using Porous Body A porous body such as an air stone has a large number of pores communicating with each other, and some of the pores are opened on the surface of the porous body. When a gas is introduced into the porous body while the porous body is immersed in the liquid, the gas passes through the pores and becomes fine bubbles from the surface of the porous body and is released into the liquid. Therefore, if the pore diameter is reduced, macro bubbles having a desired diameter can be generated. A film-like gas dispersion material may be used as the porous body.
(3) Gas-liquid stirrer The gas-liquid stirrer has a stirring member such as a screw arranged in the liquid, and rotates the stirring member at high speed while supplying the gas into the liquid, and exists as bubbles in the liquid. Stir the gas. Thereby, the bubble in a liquid is refined | miniaturized and a microbubble is produced | generated.

A gas supply source 29 is connected to the microbubble generator 28, and microbubbles are generated by the microbubble generator 28 using the gas supplied from the gas supply source 29. In the present embodiment, ozone (O ₃ ), oxygen difluoride (F ₂ O), carbon dioxide (CO ₂ ), a mixture of ozone and carbon dioxide, or the like is preferably used as the gas forming the microbubbles. It is done. These gases are appropriately selected depending on the type of substance to be processed.

For example, ozone is used when removing organic substances such as polymers and resist materials. Ozone has a strong oxidizing power, and organic substances can be decomposed into CO ₂ and removed. In addition, when removing unnecessary metals such as Cu and Al remaining on the semiconductor wafer W, oxygen difluoride is used. Fluorine dioxide has a strong oxidizing power, and can dissolve and remove metals such as Cu and Al. Note that ozone can also be used to remove the metal.

  When removing the polymer adhering to the device portion (microfabricated portion) formed on the surface of the semiconductor wafer W, a mixture of ozone and carbon dioxide is used. Further, the treatment liquid mixed with carbon dioxide can be used as a rinse liquid after polishing. The treatment liquid mixed with carbon dioxide can prevent the generation of static electricity as compared with the rinse liquid using pure water. Therefore, it is possible to prevent the device portion formed on the semiconductor wafer W from being charged.

Next, the operation of the substrate processing apparatus configured as described above will be described.
First, the motor 14 is driven to move the head 12, and the head 12 is positioned above the semiconductor wafer W held on the substrate holding unit 3. Next, the head 12 is moved downward by the air cylinder 16 to bring the ultrasonic transducer 20 close to the surface of the semiconductor wafer W. At this time, the microbubble generator 28 is driven to generate microbubbles in the processing liquid 2 in the processing liquid supply source 27.

  Next, the semiconductor wafer W is rotated by driving the motor 8, and the processing liquid 2 containing microbubbles is supplied onto the semiconductor wafer W from the processing liquid supply source 27 through the processing liquid inlet 23. The processing liquid 2 spreads outward in the radial direction of the semiconductor wafer W as the semiconductor wafer W rotates, and the processing liquid 2 eventually flows out from the peripheral edge of the semiconductor wafer W. The processing liquid 2 flowing out from the semiconductor wafer W is collected by the container 5. In this state, ultrasonic waves are irradiated from the ultrasonic transducer 20 toward the treatment liquid 2 existing between the semiconductor wafer W and the ultrasonic transducer 20.

  When ultrasonic waves are applied to the microbubbles, the microbubbles are stirred and the microbubbles are diffused throughout the treatment liquid 2. A part of the microbubbles is destroyed by ultrasonic irradiation, and a microjet flow is formed in the treatment liquid 2. An object to be processed that adheres to the semiconductor wafer W is removed using physical energy of the microjet flow. In addition, when the microbubbles are destroyed, a gas such as ozone that forms the microbubbles is dissolved in the treatment liquid 2 at a high concentration. The object to be processed on the semiconductor wafer W is removed using the chemical properties of the gas.

  The microbubbles floating in the processing liquid 2 without being destroyed can be used for removing particles floating in the processing liquid 2 and particles remaining on the semiconductor wafer W. That is, particles can be adsorbed on the surface of the microbubbles and removed by using the charging property of the microbubbles. Furthermore, the ultrasonic waves can be irradiated to the finely processed portion formed on the semiconductor wafer W by irregularly reflecting the surface of the microbubbles. As described above, according to the substrate processing apparatus according to the present embodiment, the cleaning effect by the microbubbles and the cleaning effect by the ultrasonic wave are combined, so that various objects to be processed such as particles, metals, and organic substances can be efficiently processed into a semiconductor wafer. W can be removed from above.

  The frequency of the ultrasonic wave irradiated from the ultrasonic transducer 20 is preferably 5 MHz or more and 100 MHz or less. More preferably, the frequency is 10 MHz or more and 50 MHz or less. As devices become finer in the future, ultrasonic waves in the frequency band of 1 to 5 MHz may damage the device. On the other hand, the ultrasonic wave in the frequency band of 10 to 50 MHz has no possibility of damaging the device formed on the semiconductor wafer W for the time being. Further, in the case of ultrasonic waves of 100 MHz or higher, the energy for moving the microbubbles in the processing liquid is scarce and the cleaning effect is reduced. For this reason, the ultrasonic frequency is set to 5 to 100 MHz, preferably 10 to 50 MHz.

In the present embodiment, the processing liquid 2 containing microbubbles is supplied to the semiconductor wafer W, but after supplying the processing liquid not containing microbubbles to the semiconductor wafer W, the microbubbles made of ozone are processed by electrolysis. It can also be produced in liquid. In this case, conductive diamond or lead dioxide (PbO ₂ ) is preferably used for the anode electrode portion. In order to reduce the diameter of the bubbles, a surfactant is mixed in the treatment liquid, or a pulse voltage is applied between the anode electrode portion and the cathode electrode portion.

  Next, a substrate processing system incorporating the substrate processing apparatus according to the present invention will be described in detail with reference to FIG. FIG. 3 is a plan view showing a configuration of a substrate processing system including a substrate processing apparatus according to the present invention.

  As shown in FIG. 3, this substrate processing system includes a pair of load / unload units 37 for loading / unloading a cassette (not shown) containing a semiconductor wafer W having copper as a processing object formed on the surface thereof. The apparatus includes four substrate processing apparatuses 1, a transfer robot 38 that transfers a semiconductor wafer W, and a housing 39 that accommodates these devices. A transport rail 40 is disposed at the center of the housing 39, and the transport robot 38 can freely move on the transport rail 40. Two substrate processing apparatuses 1 are disposed on both sides of the transport rail 40, and the load / unload unit 37 is disposed near the end of the transport rail 40. Between the load / unload unit 37 and the substrate processing apparatus 1, the transfer of the semiconductor wafer W is performed by the transfer robot 38.

Next, the operation of the substrate processing system configured as described above will be described.
The cassette containing the semiconductor wafer W is set in the load / unload unit 37, and one semiconductor wafer W is taken out from the cassette by the transfer robot 38. The transfer robot 38 transfers the semiconductor wafer W to the substrate processing apparatus 1 and holds it on the substrate holding unit 3 (see FIG. 1) of the substrate processing apparatus 1. Until the semiconductor wafer W is held by the substrate holder 3, the head 12 stands by at the retracted position indicated by the dotted line in FIG. 2. Then, after the semiconductor wafer W is held by the substrate holder 3, the head 12 (see FIG. 1) moves to the vicinity of the upper surface of the semiconductor wafer W, and the substrate is cleaned. Since the operation of the substrate processing apparatus 1 is as described above, the description thereof is omitted here.

  After completion of the cleaning process, the head 12 moves to the retreat position described above, and the semiconductor wafer W held on the substrate holding unit 3 is returned to the cassette of the load / unload unit 37 by the transfer robot 38. Since this substrate processing system includes four substrate processing apparatuses 1, a plurality of semiconductor wafers W can be continuously cleaned.

  The substrate processing apparatus 1 may be provided with a drying means for the semiconductor wafer W, and the drying process may be performed following the cleaning process. For example, the semiconductor wafer W on the substrate holder 3 can be centrifugally dried by rotating the rotating shaft 4 (see FIG. 1) at a high speed after the cleaning process. Further, a rinsing process for removing the processing liquid adhering to the semiconductor wafer W during the cleaning process may be performed between the cleaning process and the drying process. For example, by supplying a rinsing liquid such as ultrapure water from the processing liquid inlet 23 (see FIG. 1) onto the semiconductor wafer W, the processing liquid adhering to the semiconductor wafer W can be replaced with the rinsing liquid. Also in this rinsing treatment, it is preferable to generate microbubbles in the rinsing liquid and to irradiate the rinsing liquid with ultrasonic waves. In the present embodiment, only the front surface (upper surface) of the semiconductor wafer W is cleaned. However, a processing liquid inlet, an ultrasonic vibrator, and the like are provided on the back surface (lower surface) side of the semiconductor wafer W to provide a semiconductor. You may make it wash | clean not only the surface of the wafer W but the back surface. Even in this case, a rinsing process may be performed after the cleaning process, and a drying process may be performed between the cleaning process and the rinsing process.

It is sectional drawing which shows the whole structure of the substrate processing apparatus which concerns on one Embodiment of this invention. 1 is a plan view schematically showing a substrate processing apparatus according to an embodiment of the present invention. It is a top view which shows the structure of the substrate processing system provided with the substrate processing apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate processing apparatus 2 Processing liquid 3 Substrate holding part 4 Rotating shaft 5 Container 6 Substrate holding table 7 Support pin 8, 14 Motor 11 Arm 12 Head 13, 17 Power transmission mechanism 15 Support shaft 16 Air cylinder 20 Ultrasonic vibrator 23 Processing Liquid inlet 25 Through hole 26 Pipe 27 Processing liquid supply source 28 Micro bubble generator 29 Gas supply source 37 Load / unload unit 38 Transfer robot 39 Housing 40 Transfer rail

Claims (6)

A treatment liquid supply source for supplying the treatment liquid onto the substrate;
A microbubble generator for generating microbubbles in the processing liquid;
A substrate processing apparatus comprising: an ultrasonic transducer that irradiates a processing liquid containing microbubbles with ultrasonic waves.   The substrate processing apparatus according to claim 1, wherein the microbubble has a diameter of 20 μm or less and an internal pressure of atmospheric pressure or more.   The substrate processing apparatus according to claim 1, wherein the microbubble generator is one of a two-fluid nozzle, a gas disperser, a gas-liquid stirrer, and an electrolytic gas generator. A substrate holder for holding the substrate;
A rotation mechanism for rotating the substrate holding unit;
The substrate processing apparatus according to claim 1, wherein the ultrasonic transducer is disposed so as to face a substrate held by the substrate holding unit.   The ultrasonic vibrator has a processing liquid inlet, and the processing liquid is supplied between the ultrasonic vibrator and the substrate held on the substrate holder through the processing liquid inlet. The substrate processing apparatus according to claim 4.   The substrate processing apparatus according to claim 1, wherein the frequency of ultrasonic waves emitted from the ultrasonic transducer is 5 to 100 MHz.

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