JP4957277B2 - Cleaning device and cleaning method - Google Patents

Description

  The present invention relates to a spin cleaning apparatus for cleaning a rotating substrate with a cleaning liquid to which ultrasonic vibration is applied, and a cleaning method therefor.

(1) A spin cleaning semiconductor device using an ultrasonic nozzle is manufactured through many processes such as photoresist processing and dry etching. However, each time these steps are performed, the surface of the semiconductor substrate to be processed is contaminated. Therefore, in order to remove these contaminations, there are many cleaning steps in the semiconductor device manufacturing process.

  As a method for cleaning a semiconductor substrate, dip cleaning in which a semiconductor substrate is immersed in a cleaning tank filled with a cleaning liquid has been generally used. In this process, a batch process in which a plurality of semiconductor substrates are immersed in a cleaning solution at the same time is generally used in order to improve work efficiency.

  However, with the increase in the diameter of semiconductor substrates (semiconductor wafers), in recent years, single wafer spin cleaning has become the mainstream as a method for cleaning semiconductor substrates. This is because single-wafer spin cleaning is superior in terms of in-plane uniformity of the cleaning effect, reduction of cleaning liquid and rinsing pure water, and shortening of apparatus startup time.

  FIG. 9 shows an outline of the single wafer spin cleaning method. The substrate to be cleaned 50 made of a semiconductor substrate is sucked and fixed to a turntable (not shown) one by one and rotated at a high speed by this turntable. Next, the cleaning liquid 52 to which the ultrasonic wave is applied is sprayed from the ultrasonic nozzle 51 toward the rotating substrate to be cleaned 50. Contaminants (resist residue and the like) adhering to the surface of the substrate to be cleaned 50 are removed by the ultrasonic vibration propagating through the cleaning liquid 52.

  On the other hand, the ultrasonic nozzle 51 reciprocates in the radial direction with respect to the rotational movement of the substrate to be cleaned 50.

  By this movement, the cleaning position 55 where the cleaning liquid 52 hits the substrate 50 to be cleaned reciprocates between the rotation center 53 and the outer periphery 54 of the substrate 50 to be cleaned. Accordingly, the cleaning liquid 52 is uniformly applied to the entire surface of the substrate to be cleaned 50 by this reciprocating motion and the high speed rotation of the substrate to be cleaned 50, and the entire substrate to be cleaned 50 is cleaned.

(2) Spin cleaning by vibrator However, in many cases, the above-described spin cleaning cannot be applied to the manufacturing process of a semiconductor device belonging to the generation whose minimum wiring width is 100 nm or less.

  In order to manufacture this generation of semiconductor devices, various fine structures are formed on the surface of the semiconductor substrate. However, these structures cannot easily withstand the ultrasonic vibration of the cleaning liquid ejected from the ultrasonic nozzle and are easily destroyed. For example, a thinned photoresist film, a porous silica film for back-end wiring, and the like are easily destroyed by the spin cleaning.

  In order to prevent such destruction of the fine structure, a spin cleaning apparatus using a vibrating body has been proposed (Patent Document 1). In this method, since the ultrasonic wave is supplied to the cleaning liquid through the side surface of the vibrating body formed of a triangular prism, the vibration energy per unit area is reduced. For this reason, even the fragile microstructure formed on the semiconductor substrate does not need to be destroyed.

  FIG. 10 shows an outline of a spin cleaning method using a vibrating body. Similar to the method of cleaning using an ultrasonic nozzle, the substrate to be cleaned 50 made of a semiconductor substrate is sucked and fixed to a rotary table (not shown) one by one and rotated at a high speed by this rotary table. Next, the triangular prism-shaped vibrating body 56 is arranged so that one side surface 59 thereof and the surface to be cleaned of the substrate to be cleaned 50 face each other with an interval of about 1 mm. In this state, the cleaning liquid 52 is supplied from the nozzle 57 to the surface to be cleaned near the vibrating body 56. Then, as shown in the side view of FIG. 11, the cleaning liquid 50 enters between the vibrating body 56 and the substrate to be cleaned 50 by the rotation of the substrate 52 to be cleaned. FIG. 11 is a view of the cleaning state as viewed from the direction A shown in FIG.

  In this state, the ultrasonic vibrator 58 fixed to the other side surface of the vibrating body 56 is vibrated to generate ultrasonic waves, and the ultrasonic waves are propagated toward the side surface 59 facing the surface to be cleaned. The ultrasonic wave that has reached the side surface 59 is transmitted to the cleaning liquid 52 and propagates through the cleaning liquid 52, reaches the surface of the substrate 52 to be cleaned (that is, the surface to be cleaned), and removes contaminants. Note that the vibrating body is fixed to the arm 60. In addition, high frequency power of several MHz is supplied to the ultrasonic transducer 60 via the cable 61.

In this method, the ultrasonic waves generated by the ultrasonic transducer 58 are dispersed throughout the side surface 59 of the vibrating body 58. Therefore, the ultrasonic vibration intensity per unit area irradiated to the surface to be cleaned (that is, ultrasonic vibration energy per unit area, hereinafter referred to as the surface density of ultrasonic energy) is determined when an ultrasonic nozzle is used. It becomes much smaller than that. For this reason, even the fragile microstructure formed on the semiconductor substrate is not destroyed.
JP2003-181394

  In the above spin cleaning using a vibrator, the surface density of ultrasonic energy supplied to the surface to be cleaned is close to the minimum value necessary for cleaning contaminants in order to prevent destruction of the fine structure on the semiconductor substrate. Is set to However, the energy required for cleaning the pollutants is not constant and varies depending on the type of pollutants, the contaminated microstructure, the process that produced the pollutants, and the like. Therefore, it is necessary to appropriately adjust the surface density of the ultrasonic energy according to the type of contaminants and the generation process thereof.

  However, the vibrator has a unique vibration state determined by the material and structure, and only the ultrasonic wave having a constant vibration intensity as well as the frequency is excited by the vibrator. Therefore, even if the power supplied to the ultrasonic transducer 58 and its frequency are adjusted, it is difficult to set the surface density of the ultrasonic energy supplied to the surface to be cleaned to a desired value. If the surface density of ultrasonic energy is to be set to a desired value, a very inefficient operation of remodeling the vibrator itself must be performed. A similar situation exists for spin cleaning using an ultrasonic nozzle.

  In other words, since the surface density of ultrasonic energy used for cleaning cannot be adjusted as appropriate in the conventional spin cleaning method, contaminants are efficiently removed on the surface to be cleaned on which a microstructure that is easily destroyed is formed. There was a problem that could not be done.

  Therefore, an object of the present invention is to provide a spin cleaning apparatus and a cleaning method using the apparatus, which can easily adjust the surface density of ultrasonic energy supplied to the substrate to be cleaned.

  In order to achieve the above object, a cleaning apparatus according to a first aspect of the present invention includes a rotary table that horizontally fixes a substrate to be cleaned for a while, an ultrasonic nozzle that ejects a liquid to which ultrasonic waves are applied, and the ultrasonic wave The liquid ejected by the nozzle is irradiated, and a predetermined distance is provided between the dispersion plate for dispersing the ultrasonic waves and the substrate to be cleaned, and the dispersion plate is fixed in parallel to the substrate to be cleaned. An opening in the dispersion plate, a conduit connected to supply cleaning liquid between the substrate to be cleaned and the dispersion plate through the opening, and the liquid at any position on the dispersion plate. And a moving device that moves the ultrasonic nozzle so that the irradiation position can be moved. Here, the cleaning liquid transmits the ultrasonic waves dispersed by the dispersion plate to the substrate to be cleaned to clean the substrate to be cleaned.

  With such a configuration, according to the first invention, even if a fine structure that is very fragile is formed on the surface of the substrate to be cleaned, the highest cleaning effect is possible as long as the fine structure is not damaged. Can be obtained.

  The cleaning apparatus according to a second invention is characterized in that, in the first invention, the dispersion plate is replaceable with another dispersion plate having a different material, thickness or layer structure.

  With such a configuration, according to the second invention, even if a fine structure that is very fragile is formed on the surface of the substrate to be cleaned, the highest cleaning effect is possible as long as the fine structure is not damaged. Thus, the cleaning power of the cleaning device can be optimized.

  A cleaning apparatus according to a third aspect of the invention is characterized in that, in the first or second aspect of the invention, the cleaning apparatus includes an interval adjusting device capable of freely changing the predetermined distance.

  With such a configuration, in the third invention, the fine adjustment of the cleaning power is facilitated. Therefore, even if a fine structure that is very fragile is formed on the surface of the substrate to be cleaned, the fine structure is damaged. It becomes easy to optimize the cleaning power of the cleaning device so that the highest possible cleaning effect can be obtained within the range.

  According to a fourth aspect of the present invention, there is provided a cleaning apparatus according to any one of the first to third aspects, further comprising a height adjusting device capable of freely changing a distance between the ultrasonic nozzle and the dispersion plate.

  With such a configuration, according to the fourth invention, fine adjustment of the cleaning power is further facilitated. Therefore, even if a fine structure that is very fragile is formed on the surface of the substrate to be cleaned, this fine structure Further, it becomes easier to optimize the cleaning power of the cleaning device so that the highest possible cleaning effect can be obtained without damaging the surface.

  A cleaning apparatus according to a fifth invention is the cleaning device according to any one of the first to fourth inventions, wherein the dispersion plate has a plurality of regions having different degrees of dispersion or absorption of the ultrasonic waves transmitted by the liquid. And an ultrasonic irradiation position switching device that freely switches a position irradiated on the dispersion plate between the plurality of regions.

  With such a configuration, according to the fifth aspect of the invention, since it is possible to coarsely adjust the cleaning power without replacing the dispersion plate, a very fragile fine structure is formed on the surface of the substrate to be cleaned. Even so, it is easiest to optimize the cleaning power of the cleaning device so as to obtain the highest possible cleaning effect as long as the fine structure is not damaged.

  According to a sixth aspect of the present invention, there is provided a cleaning method in which a predetermined distance is provided between the first step of horizontally fixing the substrate to be cleaned to a rotary table for a while and the substrate to be cleaned, and the dispersion plate A second step of fixing the substrate to be parallel to the substrate, a third step of rotating the substrate to be cleaned together with the rotary table, a fourth step of supplying a cleaning liquid between the dispersion plate and the substrate to be cleaned, It is characterized by comprising a fifth step of irradiating the dispersion plate with a liquid to which ultrasonic waves are applied and reciprocating the liquid irradiation position between the center of rotation and the outer periphery of the substrate to be cleaned.

  With such a configuration, according to the sixth aspect of the invention, even if a fine structure that is very fragile is formed on the surface of the substrate to be cleaned, the highest cleaning effect is possible as long as the fine structure is not damaged. Can be obtained.

  According to the cleaning device (or dispersion plate) or the cleaning method according to the present invention, the ultrasonic energy transmitted to the dispersion plate by the ultrasonic medium liquid ejected from the ultrasonic nozzle is dispersed and attenuated (absorbed) by the dispersion plate. Therefore, the degree to which the ultrasonic waves are dispersed and attenuated by the dispersion plate can be adjusted over a wide range only by changing the thickness or material of the dispersion plate. Therefore, according to the present invention, the intensity of ultrasonic waves (surface density of ultrasonic energy) transmitted from the dispersion plate to the cleaning liquid and reaching the substrate to be cleaned can be easily adjusted over a wide range.

  Therefore, even if a very fragile fine structure is formed on the surface of the substrate to be cleaned, the spin cleaning device is optimized so that the cleaning power is maximized within a range that does not damage the fine structure. can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

(Embodiment 1)
(1) Apparatus Configuration This embodiment relates to a cleaning apparatus (or a dispersion plate) and a cleaning method that can easily adjust the surface density of ultrasonic energy supplied to a substrate to be cleaned.

  In the cleaning apparatus (or dispersion plate) and the cleaning method in the present embodiment, the ultrasonic wave is not sprayed directly onto the substrate to be cleaned, but ultrasonic waves are applied to the dispersion plate made of a flat plate such as synthetic quartz. The medium liquid applied is sprayed to disperse / attenuate the ultrasonic energy, and then the ultrasonic wave is transmitted to the cleaning liquid. Therefore, the cleaning power can be adjusted by a simple operation such as changing the thickness of the dispersion plate. For this reason, even for a substrate to be cleaned on which a fragile structure is formed, the cleaning power can be maximized within a range in which the structure is not damaged.

  FIG. 1 is a side view of the cleaning device in the present embodiment, and FIG. 2 is a plan view of the cleaning device.

  As shown in FIGS. 1 and 2, the cleaning apparatus of the present embodiment includes a rotary table 1 that vacuum-sucks a substrate to be cleaned and horizontally fixes it for a while and a liquid (for example, pure water) to which ultrasonic waves are applied. The ultrasonic nozzle 2 to be ejected, the dispersion plate 3 on the disk to which the liquid ejected by the ultrasonic nozzle 2 is irradiated, and the through-hole 15 in which the dispersion plate 3 is fixed at the center and through which the cleaning liquid flows are arranged in the axial direction The column 4 is provided, a first rotating shaft 5 that reciprocates at a predetermined rotation angle, and a support 6 that connects the ultrasonic nozzle 2 and the first rotating shaft 5.

  The support column 4 functions not only as a support for fixing the dispersion plate 3 but also as a conduit through which the cleaning liquid flows through the through hole 15 and an orifice 7 of the dispersion plate 3 described later. The support column 4 has a jig (not shown) for detachably fixing the dispersion plate to the end of the distribution plate side, for example, a ring (corresponding to the head of the bolt) fixed to the tip of the support column 4 and the support column 4 (on the bolt). It has a nut that fits into the screw engraved on If the dispersion plate 3 is sandwiched between the ring and the nut and tightened with a nut, the dispersion plate 3 can be fixed detachably. Further, the support column 4 is fixed to a mechanical vertical movement device (not shown) and can be moved up and down with an accuracy of 1 mm or less.

  Further, although not shown in FIGS. 1 and 2, the cleaning apparatus of the present embodiment includes a cleaning liquid supply apparatus that supplies a cleaning liquid between the substrate to be cleaned and the dispersion plate 3 through the through hole 15 of the support column 4. An ultrasonic medium liquid supply device for supplying the liquid (hereinafter referred to as an ultrasonic medium liquid) as a medium for propagating ultrasonic waves to the ultrasonic nozzle 2, and an ultrasonic vibrator constituting the ultrasonic nozzle 2 A high frequency power source for supplying high frequency power to the

  The dispersion plate 3 is made of a synthetic quartz disk having a thickness of 4 mm, and an orifice 7 through which the cleaning liquid that has passed through the through hole 15 of the support column 4 is discharged is opened at the center. The dispersion plate 3 is used to disperse the ultrasonic wave propagating through the ultrasonic medium liquid over a wide range and attenuate it to transmit it to the cleaning liquid. As will be described later, the material and thickness of the dispersion plate are selected so that the surface density of the ultrasonic energy supplied to the object to be cleaned via the cleaning liquid becomes a desired value. Further, the central axis 60 of the support column 4 and the central axis 61 of the turntable 1 are separated from each other by a certain distance in the parallel direction.

  FIG. 3 is a cross-sectional view of the ultrasonic nozzle 2 in the operating state. The ultrasonic nozzle 2 includes an ultrasonic vibrator 8 at the bottom of the nozzle, and an electric cable 9 for transmitting electric power supplied to the ultrasonic vibrator 8 and a conduit 10 for supplying an ultrasonic medium liquid are connected. . In the figure, an electric circuit for connecting the ultrasonic transducer 8 and the electric cable 9 is not described. The ultrasonic medium liquid flows into the ultrasonic nozzle 2 from the conduit 10, the ultrasonic waves are excited by the ultrasonic vibrator 8, and are ejected from the ejection port 11.

  The turntable 1 includes a wafer chuck 12 having a suction surface provided with a plurality of intake holes, and a second rotating shaft 13 that holds the wafer chuck horizontally. A conduit passes through the second rotary shaft 13 and is connected to the plurality of intake holes. The conduit in the rotating shaft is connected to a vacuum pump (not shown). The second rotating shaft 13 is connected to an electric motor (not shown).

(2) Operation FIG. 4 is a diagram for explaining a method of using the cleaning apparatus and its operation state in the present embodiment. The upper half of FIG. 4 is a plan view of the cleaning device in the operating state. The lower half of FIG. 4 is a schematic cross-sectional view taken along the line AA ′ (FIG. 2) of the cleaning device in the same operating state.

  The substrate to be cleaned 50 is cleaned by the following procedure.

  First, a substrate to be cleaned 50 made of a silicon wafer (8 inches in diameter) having a fine structure is vacuum-sucked on the turntable 1. That is, the substrate to be cleaned 50 is sucked into the suction hole of the wafer chuck 12 by operating a vacuum pump (not shown). Since the wafer chuck 12 is rotated at a high speed by the second rotation shaft 13, the substrate to be cleaned 50 is arranged so that the center 20 thereof coincides with the center axis 14 of the second rotation shaft 13.

  Next, the dispersion plate 3 is arranged on the substrate to be cleaned 50 in parallel with an interval of 3 mm by the above-described vertical movement device. The dispersion plate 3 is shaped so that its diameter is sufficiently larger than the diameter of the substrate to be cleaned 50. Accordingly, as shown in the upper half of FIG. 4, the substrate to be cleaned 50 is entirely covered with the dispersion plate 3. The dispersion plate 3 does not need to rotate in conjunction with the rotation of the substrate to be cleaned 50, and may be stationary while maintaining the above-mentioned distance from the substrate to be cleaned 50.

  Next, an electric motor (not shown) connected to the rotary shaft 13 is driven, and the rotary table 1 is rotated at a rotation speed of 200 rotations / minute.

  Next, a cleaning liquid supply device (not shown) is driven, and the cleaning liquid 16 flows between the dispersion plate 3 and the substrate to be cleaned 50 through the through holes 15 provided in the support columns 4. The cleaning liquid flowing between the dispersion plate 3 and the substrate to be cleaned 50 is given a centrifugal force by the rotation of the substrate to be cleaned 50 and flows from the vicinity of the center of rotation of the substrate to be cleaned 50 toward the outer periphery. As a result, a uniform flow of the cleaning liquid is formed from the vicinity of the rotation center of the substrate to be cleaned 50 toward the outer periphery, and the space formed between the dispersion plate 3 and the substrate to be cleaned 50 is filled with the flow of the cleaning liquid. The cleaning liquid that has reached the outer peripheral portion of the substrate to be cleaned 50 scatters in the free space together with contaminants washed away from the surface of the substrate to be cleaned 50. The cleaning liquid 16 is ammonia-added hydrogen-dissolved water obtained by further adding 1 ppm of ammonia to hydrogen-dissolved water obtained by dissolving 1.5 ppm of hydrogen gas in ultrapure water.

  The supply amount of the cleaning liquid per unit time, the distance between the dispersion plate 3 and the substrate to be cleaned 50, and the rotation speed of the turntable 1 are set so that the flow of the cleaning liquid 16 completely satisfies the above-described interval between the dispersion plate 3 and the substrate to be cleaned 50. Is set. If the distance between the dispersion plate 3 and the substrate to be cleaned 50 is not completely filled with the cleaning liquid and an air layer is present, ultrasonic waves cannot be efficiently transmitted from the dispersion plate 3 to the substrate to be cleaned 50 described later.

  Next, the ultrasonic nozzle 2 is moved to a position 50 mm above the dispersion plate 3. Here, the starting point for defining the distance between the dispersion plate 3 and the ultrasonic nozzle 2 is the position of the ultrasonic transducer 8 built in the ultrasonic nozzle 2. That is, the ultrasonic nozzle 2 is moved so that the built-in ultrasonic transducer 8 is positioned 50 mm above the dispersion plate 3. The distance between the ultrasonic transducer 8 and the dispersion plate 3 is adjusted in this way because the ultrasonic wave intensity applied to the dispersion plate 3 is set inside the ultrasonic nozzle 2 and the dispersion plate. This is because it is determined by the distance of 3. Note that the position of the cleaning liquid ejection port of the ultrasonic nozzle 2 (that is, the tip of the ultrasonic nozzle 2) is 10 mm above the dispersion plate 3.

  Next, the ultrasonic medium liquid supply device is driven, and an ultrasonic medium liquid made of pure water is supplied to the ultrasonic nozzle 2. At the same time, the high-frequency power source is driven, and high-frequency power having a frequency of 3 MHz and a power of 60 W is supplied to the ultrasonic vibrator 8 to the ultrasonic vibrator 8 in the ultrasonic nozzle 2. The ultrasonic vibrator 8 vibrates by the supplied high frequency power and excites ultrasonic waves having a frequency of 3 MHz to the ultrasonic medium liquid.

  The excited ultrasonic wave propagates in the ultrasonic medium liquid, is jetted from the ultrasonic nozzle 2 together with the ultrasonic medium liquid, and strikes the upper surface of the dispersion plate 3.

  The ultrasonic medium liquid 21 may be anything as long as it does not interfere with the operation of the cleaning device as long as it is a liquid that efficiently transmits ultrasonic waves. Further, the central axis 18 of the ultrasonic nozzle 2 is inclined 20 to 30 degrees with respect to the normal line 19 of the dispersion plate 3. This is because when the ultrasonic medium liquid 21 hits the dispersion plate 3 perpendicularly, the ultrasonic wave irradiated by the dispersion plate 3 travels backward in the ultrasonic medium liquid 21 and returns to the inside of the ultrasonic nozzle 2 to generate ultrasonic vibrations. This is because the child 8 may be damaged.

  The diameter when the jet flow made of the ultrasonic medium liquid 21 hits the dispersion plate 3 is 3 to 4 mm. In the conventional spin cleaning method using the ultrasonic nozzle 2, if the substrate to be cleaned is cleaned using the same ultrasonic nozzle, the region to be cleaned by irradiation with the cleaning liquid is in the range of 3 to 4 mm in diameter (this The cleaning range travels on the surface of the substrate to be cleaned by rotation of the substrate to be cleaned and the entire substrate to be cleaned is cleaned.) On the other hand, in the present embodiment, contaminants are removed in the range of 10 to 20 mm in diameter around the point irradiated with the ultrasonic medium liquid 21.

  As shown in FIG. 5, the reason why the cleaning region is greatly expanded is that the ultrasonic wavefront 22 expands while propagating through the dispersion plate 3 and the cleaning liquid 16, and the vibration energy of the ultrasonic waves is dispersed. It is. For convenience of explanation, in FIG. 5, the cleaning liquid 21 is drawn so as to enter the dispersion plate 3 perpendicularly.

The energy density of the ultrasonic waves that reach the surface of the substrate to be cleaned 50 by such a dispersion action is about 1/11 to 1/25 ((3 mm / 10 mm) ² to (4 mm) when the dispersion plate 3 is irradiated. / 20 mm) ² ). Furthermore, a part of the ultrasonic energy disappears (that is, attenuates) while propagating through the dispersion plate 3 and the cleaning liquid 16, and the ultrasonic energy reaching the substrate to be cleaned 50 further decreases.

  That is, by providing the layers of the dispersion plate 3 and the cleaning liquid 16, the surface density of the ultrasonic energy that reaches the substrate to be cleaned 50 is markedly different from the energy density of the ultrasonic waves that are irradiated onto the surface to be cleaned by the ultrasonic nozzle 2. Therefore, destruction of the fine structure formed on the surface of the substrate to be cleaned 50 is prevented.

  Moreover, the surface density of the ultrasonic energy on the surface of the substrate to be cleaned 50 depends on the material of the dispersion plate 3, the thickness of the dispersion plate 3, and the type and layer thickness of the cleaning liquid 16 (that is, the substrate 50 to be cleaned and the dispersion plate 3). By changing the (interval), it can be easily adjusted over a wide range. That is, according to the present embodiment, since the cleaning power can be easily adjusted, the substrate to be cleaned 50 can be cleaned in a state where the cleaning power is sufficiently strong as long as the fine structure is not destroyed. Therefore, contaminants can be removed from the substrate to be cleaned 50.

  The cleaning power is most dependent on the material of the dispersion plate 3. Next, depending on the thickness of the dispersion plate 3, the influence of the layer thickness of the cleaning liquid 16 is the smallest. Accordingly, when the ultrasonic nozzle 2 to be used is determined, the cleaning power is first adjusted roughly according to the material and thickness of the dispersion plate 3, and finally the distance between the substrate to be cleaned 50 and the dispersion plate 3 is adjusted. And fine-tune the cleaning power. Furthermore, when fine adjustment is necessary, the distance between the ultrasonic nozzle 2 and the dispersion plate 3 may be adjusted. This is because the energy of the ultrasonic wave is attenuated as the propagation distance increases while the ultrasonic wave is generated by the ultrasonic vibrator 8 and reaches the dispersion plate 3. If it adds, detergency will become weak, so that the dispersion plate 3 becomes thick. In addition, the thickness of the cleaning liquid layer (the distance between the substrate to be cleaned 50 and the dispersion plate 3) becomes weaker and becomes weaker as the distance between the ultrasonic nozzle 2 and the dispersion plate 3 becomes wider.

  Unlike the conventional vibrating body 56 and the ultrasonic vibrator 8 of the spin cleaning apparatus, no special design is required to produce the dispersion plate 3 with different thickness, and the degree to which ultrasonic energy is dispersed and attenuated However, it is easy to prepare a dispersion plate having a different size. Further, if the jig described above is provided at the end of the support column 4, the dispersion plate can be easily replaced. Furthermore, the distance between the substrate to be cleaned 50 and the dispersion plate 3 can be easily adjusted by using the above-described mechanical vertical movement device. Further, the height of the ultrasonic nozzle 2 can be easily adjusted. That is, according to the cleaning apparatus according to the present embodiment, the cleaning power can be easily adjusted over a wide range.

  That is, the above-described mechanical vertical movement device functions as an interval adjustment device that can freely change the distance between the dispersion plate and the substrate to be cleaned.

  On the other hand, in the conventional spin cleaning method, it is not possible to obtain a desired cleaning power by simply changing the dimensions of the ultrasonic vibrator and the vibrator. In order to obtain a desired detergency, new development activities including design changes are required. For this reason, it is practically difficult to adjust the cleaning power over a wide range.

  The material, thickness, and the like of the dispersion plate 3 shown in the present embodiment were processed into a 65 nm / 65 nm line and space by forming 200 nm thick porous silica on a silicon substrate (8 inches). This is optimized for the substrate to be cleaned 50. This fine structure is similar to the structure used when copper wiring is formed by the damascene method.

  While the ultrasonic medium liquid is being ejected, the ultrasonic nozzle 2 reciprocates on a straight line connecting the rotation center 20 of the substrate to be cleaned 50 and the outer periphery thereof. This reciprocating motion is generated by the reciprocating motion of the first rotating shaft 5 to which the ultrasonic nozzle 2 is connected by the support 6 at a predetermined rotational angle.

  By the reciprocating motion of the ultrasonic nozzle 2 and the rotation of the substrate to be cleaned 50, the entire surface of the substrate to be cleaned 50 is irradiated with ultrasonic waves to remove contaminants.

  In other words, the first rotating shaft 5 and the support 6 reciprocate between the rotation center of the substrate to be cleaned and the outer peripheral portion at the position (irradiation position) where the liquid is irradiated onto the dispersion plate by the ultrasonic nozzle 2. In addition, it functions as a moving device for moving the ultrasonic nozzle.

  If the position where the support column 4 is attached to the dispersion plate 3 is directly above the second rotating shaft 13 as shown in FIG. 6, the support column 4 becomes an obstacle and the center of the substrate to be cleaned 50 is irradiated with ultrasonic waves. It becomes difficult. Therefore, in the present embodiment, as shown in FIG. 4, the support column 4 is disposed at a position slightly shifted from directly above the second rotating shaft 13.

  After a predetermined cleaning time (for example, 60 seconds) has elapsed, the ejection of the ultrasonic medium liquid from the cleaning nozzle 2 is stopped, and pure water for rinsing is supplied from the cleaning liquid supply device instead of the cleaning liquid. Further, the reciprocating motion of the first rotating shaft 5 is also stopped. Next, after a predetermined time has elapsed and rinsing of the substrate to be cleaned 50 is completed, the supply of pure water from the cleaning liquid supply device and the rotation of the second rotary shaft 13 are stopped.

  Next, the dispersion plate 3 is removed from the substrate to be cleaned 50. Next, moisture remaining on the surface of the cleaning substrate 50 is removed with dry nitrogen. Finally, the vacuum pump is stopped, the wafer chuck 12 is leaked, and the substrate to be cleaned 50 is removed from the turntable 1.

(3) Comparison of cleaning ability The cleaning ability of the cleaning device in the present embodiment was compared with that of a conventional spin cleaning device.

  For comparison, two types of samples were prepared.

  The first sample is a substrate to be cleaned 50 in which porous silica having a thickness of 200 nm is formed on a silicon substrate (8 inches), and this porous silica is processed into a 65 nm / 65 nm line and space by dry etching. is there.

In the second sample, a thermal oxide film having a thickness of 100 nm is formed on a silicon substrate (8 inches), and silica (SiO ₂ ) particles having an average particle diameter of 0.15 μm are uniformly attached to the surface of the thermal oxide film. The substrate to be cleaned 50.

  The first sample is for evaluating damage to the substrate to be cleaned by the cleaning apparatus. On the other hand, the second sample is for evaluating the cleaning power of the cleaning device.

  Hereinafter, the cleaning ability of the cleaning device in the present embodiment and the conventional spin cleaning device will be compared. The cleaning liquid used in the test and the rotation speed of the rotary table are the same as those described in “(2) Operation”. That is, the rotation speed of the rotary table is 200 rpm, and the cleaning time is 60 seconds. The cleaning liquid is ammonia-added hydrogen-dissolved water obtained by adding 1 ppm of ammonia to hydrogen-dissolved water obtained by dissolving 1.5 ppm of hydrogen gas in ultrapure water.

  First, the first and second samples were cleaned with a spin cleaning apparatus using an ultrasonic nozzle. High frequency power having a frequency of 3 MHz and a power of 60 W was input to the ultrasonic transducer 8 in the ultrasonic nozzle. As a result of washing, 91.4% of the silica particles could be removed from the second sample. However, the line and space pattern of the first sample was damaged and broke before the original shape was retained. In response to this situation, the size and shape of the ultrasonic nozzle were variously changed, and the input power was adjusted to perform cleaning without damage. However, it was not possible to clean the pattern without damaging it.

  Next, spin cleaning was attempted using a triangular prism-shaped vibrator made of synthetic quartz. The size of the surface of the vibrating body facing the substrate to be cleaned 50 is 3 × 4 cm, and the distance between the substrate to be cleaned 50 and the vibrating body is 1 mm. High frequency power having a frequency of 3 MHz and a power of 60 W was input to the ultrasonic transducer 8 bonded to the other surface of the vibrator. As a result of the cleaning, the pattern of the second sample was not damaged at all. However, only 46.8% of silica particles could be removed from the first sample. In this situation, cleaning was attempted using various vibrators available, but the silica particle removal rate could not be increased.

  Finally, cleaning was performed using the cleaning apparatus in this embodiment. The parameters used for cleaning are the same as those described in “(1) Apparatus” or “(2) Operation”. That is, high frequency power having a frequency of 3 MHz and a power of 60 W was input to the ultrasonic transducer 8 in the ultrasonic nozzle. The dispersion plate 3 is made of synthetic quartz and has a thickness of 4 mm. The distance between the dispersion plate 3 and the substrate to be cleaned 50 was set to about 3 mm. Further, the distance between the ultrasonic transducer 8 and the dispersion plate 3 in the ultrasonic nozzle 2 is 50 mm.

  As a result of the cleaning, no damage occurred in the pattern of the second sample. In addition, 86.7% of silica particles were removed from the first sample.

  The above parameters have been previously optimized for the first sample. That is, in the cleaning apparatus according to the present embodiment, the surface density of ultrasonic energy applied to the substrate to be cleaned 50 can be easily adjusted, so that a very fragile microstructure is formed on the surface of the substrate to be cleaned 50. Even so, the surface density of the ultrasonic energy applied to the substrate to be cleaned 50 can be optimized so as to obtain the highest cleaning effect within a range in which the fine structure is not damaged.

  In addition, although the synthetic quartz was illustrated as a material of the dispersion plate 3, it is not restricted to this, For example, the board | plate material which consists of ceramics, such as an alumina board, can also be used.

(Embodiment 2)
The configuration of the cleaning apparatus in the present embodiment is the same as that of the first embodiment except that the configuration of the dispersion plate 3 is different. Also, the operation basically corresponds to the cleaning apparatus of the first embodiment. Therefore, only the configuration of the dispersion plate 3 will be described, and the description of other device configurations and operations thereof will be omitted.

  The dispersion plate 3 of Embodiment 1 has a single layer structure made of a single material. On the other hand, the dispersion plate of the present embodiment is made of a fluororesin on the synthetic quartz glass plate 23 (thickness 4 mm) as shown in the sectional view of FIG. A film 24 (thickness 0.1 mm) is attached. The thickness of the fluororesin film is one digit or more smaller than that of the synthetic quartz glass plate 23, but the degree of absorption of the irradiated ultrasonic wave is much stronger than that of the synthetic quartz glass plate 23.

  The dispersion plate 3 of the present embodiment utilizes this property. The dispersion plate 3 is effective for a fragile microstructure that is destroyed even when the dispersion plate 3 composed of a single layer of the synthetic quartz glass plate 23 is used.

  The structure of the dispersion plate 3 in the present embodiment is determined as follows. First, the thickness of the fluororesin film is adjusted within a range of, for example, 0.1 mm to 0.5 mm, and the ultrasonic intensity transmitted to the cleaning liquid 16 is roughly adjusted. Next, the thickness of the synthetic quartz glass plate 23 is adjusted in a range of 3 mm to 5 mm, for example, and finer adjustment of the ultrasonic intensity transmitted to the cleaning liquid 16 is performed. In this way, the thickness of each layer is appropriately adjusted to select the optimum one, and the structure of the dispersion plate 3 is determined. In place of the fluororesin film 24, a film made of synthetic resin such as a film made of polyethylene or a film made of PET (Polyethylene terephthalate) can be used. Further, instead of the synthetic quartz glass plate 23, a plate material made of ceramics such as an alumina plate can be used.

  Note that there is no suitable adhesive for bonding a plate made of synthetic quartz glass or the like and a synthetic resin film, and if a space is formed between these two members, the propagation of ultrasonic waves is hindered. In such a case, as shown in FIG. 7B, the synthetic resin film 25 is sandwiched between two synthetic quartz plate glass plates 23, and a liquid (for example, between the synthetic resin film 25 and each plate member 2 is used. Water) layer may be provided. In this way, the synthetic resin film 25 is fixed by the two plate members 26 and the ultrasonic wave can propagate between the synthetic resin film 25 and the plate member 2 through the liquid layer 27.

  Alternatively, stainless steel may be coated with a fluorine resin to form a multi-layered dispersion plate.

(Embodiment 3)
The configuration of the cleaning device in the present embodiment is also the same as that of Embodiments 1 and 2 except that the configuration of the dispersion plate 3 is different. Also, the operation basically corresponds to the cleaning apparatus of the first embodiment. Therefore, only the configuration of the dispersion plate 3 will be described, and the description of other device configurations and operations thereof will be omitted.

  The dispersion plate 3 of the first and second embodiments is composed of a single region having the same layer structure. On the other hand, as shown in the plan view of FIG. 8, the dispersion plate of the present embodiment is divided into four regions 28, 29, 30, and 31 having different layer structures around the support 4. In these regions, the thickness of the dispersion plate 3 is different. For example, the regions 28 to 31 are made of synthetic quartz and have thicknesses of 3 mm, 4 mm, 5 mm, and 6 mm, respectively. Further, the dispersion plate 3 is rotatably supported by the support columns 4 so that it can be fixed when the substrate to be cleaned 50 is cleaned. Further, each region may have a multilayer structure like the dispersion plate 3 described in the second embodiment, and the thickness of each layer may be changed for each region.

  In Embodiment 1 or 2, the dispersion plate 3 must be replaced in order to roughly adjust the cleaning power. On the other hand, in the present embodiment, the dispersion medium 3 may be rotated so that the ultrasonic medium liquid hits a region having a desired layer structure. Therefore, the working efficiency for roughly adjusting the cleaning power is improved.

  That is, the strut 4 is an ultrasonic irradiation position switching device that freely switches the position where the liquid ejected by the ultrasonic nozzle 2 is irradiated to the dispersion plate 3 between regions having a desired layer structure of the dispersion plate 3. Function as.

  In order to clean the substrate to be cleaned 50 using the dispersion plate 3 according to the present embodiment, first, the column 4 is placed so that the path 32 along which the ultrasonic medium liquid reciprocates comes to a desired region of the dispersion plate 3. The dispersion plate 3 is rotated as the center. Next, the dispersion plate 3 is fixed to the support column 4 with a jig (not shown) so that it does not move during cleaning. Thereafter, the substrate to be cleaned 50 is cleaned in the same manner as in the first embodiment.

  In FIG. 8, for easy understanding of the present embodiment, the position of the substrate to be cleaned 50, the rotation center 20 of the substrate to be cleaned, and the path along which the ultrasonic medium liquid reciprocates on the upper surface of the dispersion plate 3. 32 is shown.

  In the embodiment described above, as the substrate to be cleaned 50, a semiconductor having a fragile structure is taken as an example. However, the substrate to be cleaned of the present invention is not limited to this, and other substrates, for example, for flat panel displays It may be a glass substrate.

  The above embodiment is summarized as follows.

(Appendix 1)
A rotating table that fixes the substrate to be cleaned horizontally for a while,
An ultrasonic nozzle that ejects a liquid to which ultrasonic waves are applied;
A dispersion plate that is irradiated with the liquid ejected by the ultrasonic nozzle and disperses the ultrasonic wave;
A support that fixes the dispersion plate in parallel to the substrate to be cleaned at a predetermined distance from the substrate to be cleaned;
An opening in the dispersion plate, and a conduit connected to supply a cleaning liquid through the opening between the substrate to be cleaned and the dispersion plate;
A cleaning apparatus comprising: a moving device that moves the ultrasonic nozzle so that the irradiation position of the liquid can be moved to an arbitrary position on the dispersion plate.

(Appendix 2)
The cleaning apparatus according to appendix 1, wherein the dispersion plate is replaceable with another dispersion plate having a different material, thickness, or layer structure.

(Appendix 3)
The cleaning apparatus according to appendix 1 or 2, further comprising an interval adjusting device capable of freely changing the predetermined distance.

(Appendix 4)
The cleaning apparatus according to claim 1, further comprising a height adjusting device capable of freely changing a distance between the ultrasonic nozzle and the dispersion plate.

(Appendix 5)
The dispersion plate is
A first layer;
The cleaning apparatus according to any one of supplementary notes 1 to 4, wherein the cleaning apparatus includes a second layer stacked on the first layer and having a different degree of ultrasonic absorption from the first layer.

(Appendix 6)
The dispersion plate has a plurality of regions with different degrees of dispersion or absorption of the ultrasonic waves transmitted by the liquid;
The cleaning apparatus according to any one of appendices 1 to 5, further comprising an ultrasonic irradiation position switching device that freely switches a position at which the liquid is irradiated onto the dispersion plate between the plurality of regions.

(Appendix 7)
The cleaning apparatus according to any one of appendices 1 to 6, wherein a connection position of the conduit is connected to a position shifted from a rotation center of the substrate to be cleaned.

(Appendix 8)
An ultrasonic nozzle that ejects a liquid to which ultrasonic waves are applied;
A dispersion plate to which the liquid ejected by the ultrasonic nozzle is irradiated;
A support that fixes the dispersion plate in parallel to the substrate to be cleaned at a predetermined distance from the substrate to be cleaned;
A cleaning liquid supplied between the dispersion plate and the substrate to be cleaned flows, and a conduit opening into a space formed between the substrate to be cleaned and the dispersion plate;
Used in a cleaning apparatus including a moving device that moves the ultrasonic nozzle so that a position where the liquid is irradiated onto the dispersion plate reciprocates between a rotation center and an outer peripheral portion of the substrate to be cleaned. A dispersion plate,
A dispersion plate detachable from the support.

(Appendix 9)
A rotating table that fixes the substrate to be cleaned horizontally for a while,
An ultrasonic nozzle that ejects a liquid to which ultrasonic waves are applied;
A dispersion plate to which the liquid ejected by the ultrasonic nozzle is irradiated;
A support that fixes the dispersion plate in parallel to the substrate to be cleaned at a predetermined distance from the substrate to be cleaned;
A cleaning liquid supplied between the dispersion plate and the substrate to be cleaned flows, and a conduit opening into a space formed between the substrate to be cleaned and the dispersion plate;
Used in a cleaning apparatus including a moving device that moves the ultrasonic nozzle so that a position where the liquid is irradiated onto the dispersion plate reciprocates between a rotation center and an outer peripheral portion of the substrate to be cleaned. The dispersion plate,
A first layer;
A dispersion plate that is laminated on the first layer and is composed of a second layer that is different from the first layer in the degree of absorption of ultrasonic waves, and is detachable from the support.

(Appendix 10)
A rotating table that fixes the substrate to be cleaned horizontally for a while,
An ultrasonic nozzle that ejects a liquid to which ultrasonic waves are applied;
A dispersion plate to which the liquid ejected by the ultrasonic nozzle is irradiated;
A support that fixes the dispersion plate in parallel to the substrate to be cleaned at a predetermined distance from the substrate to be cleaned;
A cleaning liquid supplied between the dispersion plate and the substrate to be cleaned flows, and a conduit opening into a space formed between the substrate to be cleaned and the dispersion plate;
Used in a cleaning apparatus including a moving device that moves the ultrasonic nozzle so that a position where the liquid is irradiated onto the dispersion plate reciprocates between a rotation center and an outer peripheral portion of the substrate to be cleaned. The dispersion plate,
A dispersion plate having a plurality of regions having different degrees of dispersion or absorption of the ultrasonic waves transmitted by the liquid.

(Appendix 11)
A first step of horizontally fixing the substrate to be cleaned to the rotary table for a while;
A second step of fixing a dispersion plate in parallel to the substrate to be cleaned, with a predetermined distance between the substrate and the substrate to be cleaned;
A third step of rotating the substrate to be cleaned together with the rotary table;
A fourth step of supplying a cleaning liquid between the dispersion plate and the substrate to be cleaned;
A cleaning method comprising a fifth step of irradiating the dispersion plate with a liquid to which ultrasonic waves are applied and reciprocating the liquid irradiation position between a rotation center and an outer peripheral portion of the substrate to be cleaned. .

  The present invention can be used in the semiconductor device manufacturing industry and the semiconductor device manufacturing equipment manufacturing industry.

Side view of cleaning apparatus according to Embodiment 1 of the present invention. The top view of the washing | cleaning apparatus in Embodiment 1 of this invention Sectional drawing of the ultrasonic nozzle in Embodiment 1 of this invention The figure for demonstrating the usage method and operation state of the washing | cleaning apparatus in Embodiment 1 of this invention. The figure explaining the dispersion | distribution / attenuation | damping process of the ultrasonic wave by the dispersion | distribution plate and the washing | cleaning liquid in Embodiment 1 of this invention Schematic explaining the motion of the ultrasonic nozzle in Embodiment 1 of this invention. Sectional drawing for demonstrating the structure of the dispersion plate in Embodiment 2 of this invention Sectional drawing for demonstrating the structure of the dispersion plate in Embodiment 3 of this invention The perspective view explaining the concept of the conventional spin cleaning using an ultrasonic nozzle First perspective view for explaining the concept of conventional spin cleaning using a vibrator Second perspective view for explaining the concept of conventional spin cleaning using a vibrator

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rotary table 2 Ultrasonic nozzle 3 Dispersing plate 4 Support | pillar 5 1st rotating shaft 6 Support body 7 Orifice 8 Ultrasonic vibrator 9 Cable 10 Pipe | tube 11 Injection port 12 Wafer chuck 13 2nd rotating shaft 15 It was provided in the support | pillar Through hole 16 Cleaning liquid 20 Center of rotation of substrate to be cleaned 21 Ultrasonic medium liquid 22 Ultrasonic wavefront 23 Synthetic quartz glass plate 24 Film made of fluororesin 25 Synthetic resin film 27 Layer of liquid 32 Path along which ultrasonic medium liquid reciprocates 50 Substrate to be cleaned

Claims (6)

A rotating table that fixes the substrate to be cleaned horizontally for a while,
An ultrasonic nozzle that ejects a liquid to which ultrasonic waves are applied;
A dispersion plate that is irradiated with the liquid ejected by the ultrasonic nozzle and disperses the ultrasonic wave;
A support that fixes the dispersion plate in parallel to the substrate to be cleaned at a predetermined distance from the substrate to be cleaned;
An opening in the dispersion plate, and a conduit connected to supply a cleaning liquid through the opening between the substrate to be cleaned and the dispersion plate;
A cleaning apparatus comprising: a moving device that moves the ultrasonic nozzle so that the irradiation position of the liquid can be moved to an arbitrary position on the dispersion plate.   The cleaning apparatus according to claim 1, wherein the dispersion plate is replaceable with another dispersion plate having a different material, thickness, or layer structure.   The cleaning apparatus according to claim 1, further comprising an interval adjustment device that can freely change the predetermined distance.   The cleaning apparatus according to claim 1, further comprising a height adjusting device capable of freely changing a distance between the ultrasonic nozzle and the dispersion plate. The dispersion plate has a plurality of regions with different degrees of dispersion or absorption of the ultrasonic waves transmitted by the liquid;
The cleaning apparatus according to claim 1, further comprising an ultrasonic irradiation position switching device that freely switches a position at which the liquid is irradiated to the dispersion plate between the plurality of regions. A first step of horizontally fixed to the rotary table to be cleaned substrate,
A second step of fixing a dispersion plate in parallel to the substrate to be cleaned, with a predetermined distance between the substrate and the substrate to be cleaned;
A third step of rotating the substrate to be cleaned together with the rotary table;
A fourth step of supplying a cleaning liquid between the dispersion plate and the substrate to be cleaned;
It comprises a fifth step of irradiating a part of the dispersion plate with a liquid to which ultrasonic waves are applied, and reciprocating the liquid irradiation position between the rotation center and the outer periphery of the substrate to be cleaned. How to wash.

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