JP5015763B2 - Substrate cleaning method, substrate cleaning apparatus, program, and program recording medium - Google Patents

Description

  The present invention relates to a substrate cleaning method and a substrate cleaning apparatus that removes particles adhering to a substrate by immersing a substrate to be processed in a cleaning solution and irradiating the cleaning solution with ultrasonic waves, and in particular, the removal efficiency of particles between lots. The present invention relates to a substrate cleaning method and a substrate cleaning apparatus that can suppress fluctuations.

  In addition, the present invention is a substrate cleaning method for removing particles adhering to a substrate by immersing the substrate to be processed in the cleaning solution and irradiating the cleaning solution with ultrasonic waves, and suppresses fluctuations in particle removal efficiency between lots. The present invention relates to a program for executing a substrate cleaning method that can be performed, and a program recording medium that stores the program.

A method of immersing a substrate to be processed in a cleaning liquid and generating ultrasonic waves in the cleaning liquid to clean the substrate to be processed, so-called ultrasonic cleaning (including megasonic processing) is known from Patent Document 1, for example. In many cases in ultrasonic cleaning, particularly when a chemical solution is used as a cleaning solution, the cleaning solution overflowing from the cleaning bath is circulated and supplied to the cleaning bath for reuse.
Japanese Patent Laid-Open No. 10-109072

  By the way, when the substrate is cleaned by ultrasonic cleaning, the particle removal efficiency may vary greatly between lots. In particular, when the cleaning liquid is circulated and supplied, fluctuations in removal efficiency tend to increase.

  As a result of investigation by the present inventors, when a plurality of lots are subjected to ultrasonic cleaning, the dissolved concentration of the gas dissolved in the cleaning liquid is caused with the passage of time due to the irradiation of ultrasonic waves or the dissolution of the atmosphere. It was discovered that it would change. It has also been found that the dissolved gas concentration varies greatly, particularly when the cleaning liquid is circulated. FIG. 8 shows a change in dissolved gas concentration over time when four lots are sequentially cleaned using the cleaning solution supplied in circulation. In this example, although the first lot and the fourth lot were cleaned under the same processing conditions (240 W, 5 minutes), the particle removal efficiency of the first lot was 72%, and the particle removal efficiency of the second lot was It was 91%.

  Generally, as described in Patent Document 1, the particle removal efficiency is said to be affected by the dissolved gas concentration of the cleaning liquid. Therefore, in order to suppress the fluctuation of the particle removal efficiency between lots, it is effective to make the dissolved gas concentration of the cleaning liquid uniform between lots.

  However, gas-dissolved concentration measuring instruments with chemical resistance are extremely expensive, and considering the price of general substrate cleaning equipment, the chemical-resistant dissolved concentration measuring equipment is built into mass-production substrate cleaning equipment. Is not realistic. Therefore, it is difficult to grasp the gas dissolved concentration of the changing cleaning liquid at present. In addition, a dissolving device that dissolves gas in the cleaning liquid and a degassing device that degass the cleaning liquid require a large installation space and complicate the control of the substrate cleaning apparatus. That is, even if the dissolved gas concentration can be grasped, another problem occurs.

  The present invention has been made in consideration of such points, and an object of the present invention is to provide a substrate cleaning method capable of suppressing variations in particle removal efficiency between lots by a simple method.

  It is another object of the present invention to provide a substrate cleaning apparatus having a simple configuration and capable of suppressing variations in particle removal efficiency between lots.

  Furthermore, the present invention provides a program for executing a substrate cleaning method capable of suppressing variations in particle removal efficiency between lots by a simple method, and a program recording medium storing the program. With the goal.

  In the first substrate cleaning method according to the present invention, the gas dissolved in the cleaning liquid in the cleaning tank is supplied by supplying gas into the cleaning tank in a state where the irradiation of ultrasonic waves to the cleaning liquid in the cleaning tank is stopped. And a step of irradiating the cleaning liquid in the cleaning tank with ultrasonic waves to clean the substrate immersed in the cleaning liquid in the cleaning tank.

  In the first substrate cleaning method according to the present invention, the step of setting the gas dissolved concentration of the cleaning liquid to a saturated concentration may be performed before immersing the substrate to be processed in the cleaning liquid in the cleaning tank. Such a substrate cleaning method is a step performed after the step of setting the gas dissolved concentration of the cleaning liquid to a saturated concentration, and the cleaning liquid in the cleaning tank is irradiated with ultrasonic waves to the cleaning liquid in the cleaning tank. And a step of adjusting the dissolved gas concentration of the cleaning liquid and a step of adjusting the dissolved gas concentration of the cleaning liquid, wherein the substrate is immersed in the cleaning liquid in the cleaning tank. Also good.

  Further, in the first substrate cleaning method according to the present invention, the step of setting the gas dissolved concentration of the cleaning liquid to the saturated concentration is performed after the substrate cleaned in the step of cleaning the substrate is taken up from the cleaning liquid in the cleaning tank. It may be implemented. In such a substrate cleaning method, before the substrate to be processed next is immersed in the cleaning liquid in the cleaning tank, the cleaning liquid in the cleaning tank is irradiated with ultrasonic waves, and the gas of the cleaning liquid in the cleaning tank is You may make it further provide the process of adjusting a dissolved concentration.

  Furthermore, in the first substrate cleaning method according to the present invention, the step of cleaning the substrate includes a step of setting the gas dissolved concentration of the cleaning liquid to a saturated concentration and a step of setting the gas dissolved concentration of the cleaning liquid to a saturated concentration. It may be carried out at least twice later. Alternatively, in the first substrate cleaning method according to the present invention, the step of cleaning the substrate is performed twice or more, and the step of setting the gas dissolved concentration of the cleaning liquid to a saturated concentration is also performed twice or more. The step of setting the dissolved concentration to the saturation concentration may be performed between the step of cleaning the substrate and the step of cleaning the substrate.

  Furthermore, in the first substrate cleaning method according to the present invention, the gas may be supplied into a cleaning liquid flowing toward the cleaning tank and supplied into the cleaning tank together with the cleaning liquid. In such a substrate cleaning method, the gas may be supplied into a cleaning liquid which is circulated and supplied again into the cleaning tank after overflowing from the cleaning tank.

  Alternatively, in the first substrate cleaning method according to the present invention, the gas may be directly supplied into the cleaning tank.

  A second substrate cleaning method according to the present invention includes a step of supplying a cleaning solution having a saturated concentration to a cleaning tank, storing the cleaning solution having a saturated concentration in the cleaning tank, and irradiating the cleaning liquid in the cleaning tank with ultrasonic waves. And a step of cleaning the substrate immersed in the cleaning liquid in the cleaning tank.

  A second substrate cleaning method according to the present invention includes a step of irradiating a cleaning liquid stored in the cleaning tank with ultrasonic waves to adjust a dissolved gas concentration of the cleaning liquid in the cleaning tank, and a cleaning liquid in the cleaning tank. A step of immersing the substrate in the substrate, and the step of immersing the substrate is performed after the step of saturating the gas dissolved concentration of the cleaning liquid and before the step of cleaning the substrate. You may do it.

  The first or second substrate cleaning method according to the present invention includes a step of discharging the cleaning liquid stored in the cleaning tank from the cleaning tank before the substrate to be processed next is accommodated in the cleaning tank. You may make it provide further.

  In the step of cleaning the substrate of the first or second substrate cleaning method according to the present invention, the cleaning liquid overflowing from the cleaning tank may be circulated and supplied into the cleaning tank. Alternatively, in the step of cleaning the substrate of the first or second substrate cleaning method according to the present invention, the supply of the cleaning liquid into the cleaning tank may be stopped.

  Furthermore, the first or second substrate cleaning method according to the present invention may further include a step of adjusting the temperature of the cleaning liquid in the cleaning tank. The step of adjusting the temperature is preferably performed before the step of bringing the dissolved gas concentration of the cleaning liquid to a saturated concentration.

  A first substrate cleaning apparatus according to the present invention is connected to a cleaning tank capable of accommodating a substrate and storing a cleaning liquid, an ultrasonic generator for irradiating ultrasonic waves to the cleaning liquid in the cleaning tank, and the cleaning tank. A supply pipe for supplying a cleaning liquid into the cleaning tank; a gas supply pipe connected to the cleaning tank or the supply pipe for supplying gas into the cleaning liquid; a gas supply from the gas supply pipe; and the ultrasonic wave And a control device for controlling the irradiation of ultrasonic waves by the generator, wherein the control device stops the irradiation of ultrasonic waves to the cleaning liquid in the cleaning tank by the ultrasonic generator. The gas supply and the ultrasonic irradiation are controlled so that the gas is supplied from the supply pipe and the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank is set to a saturated concentration.

  In the first substrate cleaning apparatus according to the present invention, the control device supplies the gas and the superconcentration so that the gas dissolved concentration of the cleaning liquid is saturated before the substrate is accommodated in the cleaning tank and immersed in the cleaning liquid. Sound wave irradiation may be controlled. In such a substrate cleaning apparatus, the control device is configured to set the gas dissolved concentration of the cleaning liquid to a saturated concentration, and before the substrate is accommodated in the cleaning tank and immersed in the cleaning liquid, Gas supply and ultrasonic irradiation may be controlled so as to adjust the dissolved gas concentration of the cleaning liquid in the cleaning tank by irradiating the cleaning liquid with ultrasonic waves.

  Further, in the first substrate cleaning apparatus according to the present invention, the control device irradiates the cleaning liquid in the cleaning tank with ultrasonic waves to clean the substrate immersed in the cleaning liquid in the cleaning tank, and is further cleaned. After the substrate is taken out from the cleaning liquid in the cleaning tank, the gas supply and the ultrasonic irradiation may be controlled so that the dissolved gas concentration of the cleaning liquid becomes a saturated concentration. In such a substrate cleaning apparatus, the control device irradiates the cleaning liquid in the cleaning tank with ultrasonic waves before immersing the substrate to be processed next in the cleaning liquid in the cleaning tank, and Gas supply and ultrasonic irradiation may be controlled to adjust the dissolved gas concentration of the cleaning liquid.

  Furthermore, in the first substrate cleaning apparatus according to the present invention, the control device irradiates the cleaning liquid in the cleaning tank with ultrasonic waves and is cleaning the substrate immersed in the cleaning liquid in the cleaning tank. Gas supply and ultrasonic irradiation may be controlled so that the ultrasonic wave irradiation to the cleaning liquid in the cleaning tank by the ultrasonic generator is temporarily stopped and the dissolved gas concentration of the cleaning liquid is set to a saturated concentration. .

  A second substrate cleaning apparatus according to the present invention includes a cleaning tank that can accommodate a substrate and stores a cleaning liquid, an ultrasonic generator that irradiates the cleaning liquid in the cleaning tank with ultrasonic waves, and an ultrasonic generator that uses the ultrasonic generator. A control device for controlling the irradiation of sound waves, and the control device irradiates the cleaning liquid stored in the cleaning tank with ultrasonic waves before the substrate is accommodated in the cleaning tank and immersed in the cleaning liquid. The ultrasonic irradiation is controlled so as to adjust the dissolved gas concentration of the cleaning liquid in the cleaning tank.

  The second substrate cleaning apparatus according to the present invention further includes a discharge pipe for discharging the cleaning liquid in the cleaning tank, and the control device is configured to store the substrate to be processed next in the cleaning tank before The cleaning liquid stored in the cleaning tank may be configured to be discharged from the cleaning tank through the drain pipe.

  The second substrate cleaning apparatus according to the present invention further includes a supply pipe connected to the cleaning tank for supplying a cleaning liquid into the cleaning tank, the supply pipe cleaning the cleaning liquid overflowing from the cleaning tank. You may be comprised so that it may circulate and supply in a tank. Alternatively, the second substrate cleaning apparatus according to the present invention further includes a supply pipe connected to the cleaning tank for supplying a cleaning liquid into the cleaning tank, and the supply pipe irradiates the cleaning liquid in the cleaning tank with ultrasonic waves. While being performed, the supply of the cleaning liquid into the cleaning tank may be stopped.

  The first or second substrate cleaning apparatus according to the present invention further includes an adjusting mechanism for adjusting the temperature of the cleaning liquid, and the control device controls the adjusting mechanism to adjust the temperature of the cleaning liquid in the cleaning tank. May be. The temperature of the cleaning liquid is preferably adjusted before the gas concentration of the cleaning liquid is saturated.

  A first recording medium according to the present invention is a recording medium on which a program executed by a control device that controls a substrate cleaning apparatus is recorded, and the program is executed by the control device, so that A step of supplying a gas into the cleaning tank to make the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank into a saturated concentration in a state where irradiation of ultrasonic waves to the cleaning liquid is stopped; And irradiating the cleaning liquid with an ultrasonic wave to clean the substrate immersed in the cleaning liquid in the cleaning tank.

  The first program according to the present invention is a program that is executed by a control device that controls the substrate cleaning apparatus, and stops the irradiation of ultrasonic waves to the cleaning liquid in the cleaning tank by being executed by the control device. In the state, supplying a gas into the cleaning tank, the step of making the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank a saturated concentration, and irradiating the cleaning liquid in the cleaning tank with ultrasonic waves, Cleaning the substrate immersed in the cleaning liquid in the cleaning tank, and causing the substrate cleaning apparatus to perform a method for cleaning the substrate to be processed.

  A second recording medium according to the present invention is a recording medium on which a program to be executed by a control device that controls the substrate cleaning device is recorded, and when the program is executed by the control device, a cleaning solution having a saturated concentration is obtained. And cleaning the substrate immersed in the cleaning liquid in the cleaning tank by irradiating the cleaning liquid in the cleaning tank with ultrasonic waves. And a step of causing the substrate cleaning apparatus to perform the substrate cleaning method.

  A second program according to the present invention is a program executed by a control device that controls a substrate cleaning apparatus, and is executed by the control device to supply a cleaning solution having a saturated concentration to the cleaning tank, and the cleaning tank A step of storing a cleaning solution having a saturated concentration therein, and a step of irradiating the cleaning solution in the cleaning tank with ultrasonic waves to clean the substrate immersed in the cleaning solution in the cleaning tank. A cleaning method is performed by a substrate cleaning apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, the gas dissolved density | concentration which melt | dissolved in the washing | cleaning liquid in a washing tank can be rapidly made into a saturated density | concentration with a simple method using the board | substrate cleaning apparatus which has a simple structure. Therefore, when processing substrates of different lots, the conditions relating to the dissolved gas concentration can be quickly aligned by a simple method. As a result, it is possible to suppress variation in the particle removal efficiency between lots due to the difference in dissolved gas concentration.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following embodiments, an example will be described in which the substrate cleaning apparatus according to the present invention is applied to a semiconductor wafer (also simply referred to as a wafer) cleaning apparatus. However, the substrate cleaning apparatus according to the present invention is not limited to application to cleaning of a semiconductor wafer, and can be widely applied to cleaning of a substrate.

  1 to 6 are diagrams for explaining an embodiment of a substrate cleaning method, a substrate cleaning apparatus, a program, and a recording medium according to the present invention. 1 is a diagram showing a schematic configuration of the substrate cleaning apparatus, and FIG. 2 is a cross-sectional view of the substrate cleaning apparatus taken along line II-II in FIG.

  As shown in FIGS. 1 and 2, the substrate cleaning apparatus 10 in the present embodiment includes a cleaning tank (DIP tank) 12, a cleaning liquid supply apparatus 40 that is connected to the cleaning tank 12 and supplies a cleaning liquid into the cleaning tank 12. A holding member (also called a wafer boat) 20 that holds the wafer W to be processed, an ultrasonic generator 30 that generates ultrasonic waves in the cleaning liquid in the cleaning tank 12, a cleaning liquid supply apparatus 40, and an ultrasonic generator 30. And a control device 18 connected to. Such a substrate cleaning apparatus 10 is an apparatus for ultrasonically cleaning the processing target wafer W by generating ultrasonic waves in the cleaning liquid in a state where the processing target wafer W is immersed in the cleaning liquid stored in the cleaning tank 12. .

  First, the cleaning liquid supply device 40 will be described in detail. As shown in FIG. 1, the cleaning liquid supply device 40 has a supply pipe (cleaning liquid supply pipe) 41 connected to the cleaning tank 12. The supply pipe 41 is connected to a return pipe 44 connected to the cleaning tank 12 through a circulation pump 45. The return pipe 44 collects the cleaning liquid overflowing from the cleaning tank 12, and as a result, the supply pipe 41 and the return pipe 44 form a circulation path to the cleaning tank 12. The cleaning liquid circulates in the cleaning tank 12, the return pipe 44, and the supply pipe 41 by pumping with the circulation 45 pump. As such a circulation pump 45, for example, an air-driven bellows pump capable of adjusting the discharge amount by adjusting the air pressure can be used.

The supply pipe 41 is also connected to the pure water source 50 via the connecting pipe 51. The pure water source 50 supplies pure water (DIW) into the connecting pipe 50 via the connecting pipe 41.
The connecting pipe 50 is provided with an open / close valve (not shown). This on-off valve is connected to the control device 18, and the control device 18 controls the operation of this on-off valve. By controlling this on-off valve, the supply of pure water from the pure water source 50 to the supply pipe 41 via the connecting pipe 51 is controlled.

  Further, as shown in FIG. 1, the supply pipe 41 has a temperature adjusting mechanism 46 for adjusting the temperature of the cleaning liquid flowing in the supply pipe 41, and impurities (particles, etc.) are removed from the cleaning liquid flowing in the supply pipe 41. And a filter 47 for cleaning the cleaning liquid. In the present embodiment, the temperature adjustment mechanism 46 is configured as a heater that heats the supply pipe 41. The temperature adjustment mechanism 46 is connected to the control device 18 so that the control device 18 controls the operation of the temperature adjustment mechanism 46.

  As shown in FIGS. 1 and 2, two cleaning liquid nozzles (cleaning liquid discharge members) 42 are provided along the opposing wall surfaces of the cleaning tank 12 at the end of the supply pipe 41 on the cleaning tank 12 side (downstream side). ing. The cleaning liquid nozzle 42 is formed of a cylindrical member extending in an elongated shape along the wall surface of the cleaning tank 12. As shown in FIG. 2, the cylindrical member is provided with a number of nozzle holes 42 a arranged at regular intervals along the longitudinal direction. The arrangement position of the nozzle hole 42a is determined based on the arrangement position of the wafer W held by the holding member 20, as will be described later.

  By the way, as described above, the cleaning liquid supply device 40 is connected to the control device 18 and is controlled by the control device 18. Specifically, the control device 18 controls the drive and stop of the circulation pump 45, the discharge amount of the circulation pump when the circulation pump 45 is driven, and the like. When the circulation pump 45 is an air-driven bellows pump, the air pressure is controlled. When the circulation pump 45 is not an air-driven bellows pump, for example, the amount of electric power to be input is controlled. Thus, the discharge amount of the pump when the circulation pump 45 is driven can be adjusted.

  As shown in FIG. 1, the substrate cleaning apparatus 10 further includes a gas supply device 60 connected to the supply pipe 41 of the cleaning liquid supply device 40. The gas supply device 60 supplies gas to the cleaning liquid that flows in the supply pipe 41 toward the cleaning tank 12. The gas supply device 60 includes a first gas source 69a that supplies a first gas, a second gas source 69b that supplies a second gas of a type different from the first gas, a first gas source 69a, and a first gas source 69a. A gas supply pipe 62 that connects the two gas sources 69b and the cleaning liquid supply pipe 41; In the present embodiment, the first gas source 69a supplies nitrogen, and the second gas source 69b supplies oxygen.

  The gas supply pipe 62 branches on the upstream side into a first gas supply pipe 62a that communicates with the first gas source 69a and a second gas supply pipe 62b that communicates with the second gas source 69b. The first gas supply pipe 62a includes a regulator 67a that adjusts the pressure in the first gas supply pipe 62a from the upstream side toward the downstream side, and a mass flow meter that measures the flow rate of the gas flowing in the first gas supply pipe 62a. 66a, a filter 65a for cleaning the gas flowing in the first gas supply pipe 62a, and an on-off valve 64a for opening and closing the first gas supply pipe 62a. Similarly to the first gas supply pipe 62a, the second gas supply pipe 62b is also provided with a regulator 67b, a mass flow meter 66a, a filter 65b, and an on-off valve 64b.

  As shown in FIG. 1, a gas supply member 61 is provided at the downstream end of the gas supply pipe 62. The gas supply member 61 supplies the gas supplied from the gas supply pipe 62 in the cleaning liquid flowing in the cleaning liquid supply pipe 41 as bubbles. In order to enable the gas to be dissolved quickly in the cleaning liquid, it is preferable that the gas supply member 61 can subdivide the gas to form minute bubbles. As such a gas supply member 61, for example, a commercially available mixer as a member for mixing a gas with a liquid, a discharge member made of a porous material and disposed in the cleaning liquid supply pipe 41, or the like can be used. . Moreover, as shown in FIG. 1, in this Embodiment, the gas supply member 61 is arrange | positioned in the downstream of the filter 47 in which the pressure of the circulation path to the washing tank 12 falls large.

  Such a gas supply device 60 is connected to the control device 18 and is controlled by the control device 18. Specifically, the gas supply device 60 is configured to supply the first gas at a supply amount (unit is, for example, 1 / min) set in advance according to the flow rate of the cleaning liquid flowing through the supply pipe 41 based on a signal from the control device 18. The second gas is discharged into the cleaning liquid supply pipe 41.

  Further, as shown in FIG. 1, the substrate cleaning apparatus 10 further includes a chemical element supply device 55 connected to the supply pipe 41 of the cleaning liquid supply device 40. The chemical element supply device 55 supplies the chemical into the cleaning liquid flowing in the connecting pipe 50. That is, by supplying a chemical from the chemical element supply device 55, when the chemical is circulating as a cleaning liquid in the supply pipe 41, the concentration of the chemical can be adjusted. When water is flowing in the supply pipe 41 as a cleaning liquid, a chemical solution with a predetermined concentration can be generated.

The chemical element supply device 55 is connected to the mixing valve 56 attached to the supply pipe 41 and the mixing valve 56, and supplies the chemical element (the drug itself or a high concentration chemical) to the mixing valve 56. A first chemical element supply source 57 and a second chemical element supply source 58. In the present embodiment, hydrogen peroxide is supplied from the first chemical element supply source 57 as the first chemical element, and ammonia is supplied from the second chemical element supply source 58 as the second chemical element. Therefore, hydrogen peroxide and ammonia are supplied into the supply pipe 41 from the first chemical element supply source 57 and the second chemical element supply source 58, and the pure water in the supply pipe 41 is mixed with these hydrogen peroxide and ammonia. By doing so, ammonia overwater SC1 (NH ₄ OH / H ₂ O ₂ / H ₂ O) can be supplied into the cleaning tank 12.

  Such a chemical element supply device 55 is connected to the control device 18 and is controlled by the control device 18. Specifically, the chemical element supply device 55 is first configured with a supply amount (unit is, for example, 1 / min) set in advance according to the flow rate of the cleaning liquid flowing through the supply pipe 41 based on a signal from the control device 18. The chemical liquid element and the second chemical liquid element are discharged into the cleaning liquid supply pipe 41.

  Next, the cleaning tank 12 that receives the cleaning liquid from the cleaning liquid supply apparatus 40 will be described. The cleaning tank 12 has a substantially rectangular parallelepiped outline as shown in FIGS. 1 and 2. The cleaning tank 12 is formed with an upper opening for taking in and out the wafer W as will be described later. A discharge pipe 13 for discharging the stored cleaning liquid is provided on the bottom surface of the cleaning tank 12 so as to be openable and closable.

  Moreover, as shown in FIG. 1, the outer tank 15 is provided so that the upper opening of the washing tank 12 may be surrounded. The outer tank 15 collects the cleaning liquid overflowing from the upper opening of the cleaning tank 12. Similarly to the cleaning tank 12, a discharge pipe 16 for discharging the recovered cleaning liquid is provided in the outer tank 15 so as to be openable and closable. Such a washing tank 12 and an outer tank 15 are formed using, for example, quartz having a high chemical resistance.

  As shown in FIG. 1, the end on the cleaning tank side of the return pipe 44 of the cleaning liquid supply apparatus 40 described above is connected to the outer tank 15. Therefore, the cleaning liquid overflowing from the cleaning tank 12 to the outer tank 15 can be circulated into the cleaning tank 12 via the return pipe 44 and the supply pipe 41. However, the cleaning liquid overflowing from the cleaning tank 12 to the outer tank 15 can be discarded as it is through the discharge pipe 16.

Next, the holding member 20 that holds the wafer W will be described. As shown in FIGS. 1 and 2, the holding member 20 has four rod-shaped members 22 extending in a substantially horizontal direction and a base portion 24 that cantilever-supports the four rod-shaped members 22 from one side. . The rod-shaped holding member 22 is configured to support a plurality of wafers W, for example, 50 wafers W to be cleaned at a time, from below.
For this reason, each rod-like member 22 is formed with grooves (not shown) arranged at regular intervals along the longitudinal direction. The wafer 20 is engaged with the groove, and the holding member is formed so that the plate surface of each wafer W is substantially orthogonal to the extending direction of the rod-like member, that is, the plate surface of each wafer W is along the vertical direction. 20 (see FIG. 1).

  As can be understood from FIG. 2, the arrangement pitch of the nozzle holes 42 a of the cleaning liquid nozzle 42 described above is substantially the same as the arrangement pitch of the wafers W held by the holding member 20. Further, the numerous nozzle holes 42 a of the cleaning liquid nozzle 42 described above are arranged so that the cleaning liquid can be discharged between the wafers W held by the holding member 20.

  On the other hand, the base 24 of the holding member 20 is connected to a lifting mechanism (not shown). The wafer W can be immersed in the cleaning liquid stored in the cleaning tank 12 by lowering the holding member 20 holding the wafer W by the lifting mechanism. The elevating mechanism is connected to the control device 18, and the control device 18 controls the immersion of the wafer W in the cleaning liquid.

  Next, the ultrasonic generator 30 will be described. As shown in FIG. 1, the ultrasonic generator 30 is connected to a vibrator 38 attached to the bottom outer surface of the cleaning tank 12, a high frequency drive power source 32 for driving the vibrator 38, and a high frequency drive power source 32. And an ultrasonic oscillator 34. In the present embodiment, a plurality of vibrators 38 are provided, and the vibrators 38 are arranged so as to partially occupy the outer surface of the bottom of the cleaning tank 12. As shown in FIG. 1, the ultrasonic generator 30 further includes a drive switching mechanism 36 connected to the ultrasonic oscillator 34 and each transducer 38. With this drive switching mechanism 36, it is possible to drive the plurality of vibrators 38 as a whole or to individually drive one or two or more vibrators 38.

  When the vibrator 38 is driven to vibrate, ultrasonic waves propagate to the cleaning liquid stored in the cleaning tank 12 through the bottom of the cleaning tank 12, thereby generating ultrasonic waves in the cleaning liquid in the cleaning tank 12. . The ultrasonic generator 30 is connected to the control device 18 so that the control device 18 controls the irradiation (applying) of ultrasonic waves to the cleaning liquid.

  Next, the control device 18 will be described. As described above, the control device 18 is connected to each component of the substrate cleaning apparatus 10 and controls the operation of each component. In the present embodiment, the control device 18 includes a computer, and the computer executes a program stored in advance in the recording medium 19 so that the wafer W to be processed is cleaned using the substrate cleaning device 10. It has become.

Next, an example of a wafer W cleaning method using the substrate cleaning apparatus 10 having the above-described configuration will be described with reference mainly to Table 1 and FIGS. 3 to 6. Here, Table 1 is a table showing the outline of the substrate cleaning method, and FIG. 3 shows the change in the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank 12 when the substrate is cleaned by the method shown in Table 1. It is a graph to show.

First, as a first step, the cleaning liquid is stored in the cleaning tank 12. Specifically, pure water is supplied from the pure water source 50 to the supply pipe 41 via the connecting pipe 51 according to a signal from the control device 18. Further, hydrogen peroxide is supplied to the supply pipe 41 from the first chemical element supply source 57 of the chemical element supply apparatus 55, and ammonia is supplied to the supply pipe 41 from the second chemical element supply source 57.
As a result, the cleaning liquid as the chemical liquid SC <b> 1 at, for example, 20 ° C. is supplied into the cleaning tank 12 through the cleaning nozzle 56 of the cleaning liquid supply device 40. At this time, the controller 18 supplies the pure water supplied from the pure water source 50, the supply amount of the first chemical liquid element supplied from the first chemical liquid element supply source 57, and the second chemical liquid according to a preset program. The supply amount of the second chemical element supplied from the element supply source 58 is controlled.

  Here, as shown in FIG. 3, in the present embodiment, the pure water supplied from the pure water source 50 is deaerated beforehand. Therefore, at the end t1 of the first step, the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank 12 is 0 ppm.

  As described above, at time t1 in FIG. 3, the cleaning tank 12 is filled with the cleaning liquid (SC1) having a dissolved gas concentration of approximately 0 ppm, and the cleaning liquid overflows from the cleaning tank 12 to the outer tank 15 and returns. The tube 44 is also filled with the cleaning liquid (SC1).

  Next, as a second step, the temperature of the cleaning liquid is adjusted. Specifically, first, the supply of pure water from the pure water source 50 to the supply pipe 41 is stopped. On the other hand, the circulation pump 45 is driven by the control device 18. As a result, the cleaning liquid circulates in the circulation path formed by the cleaning tank 12, the return pipe 44 and the supply pipe 41. As an example, when the volume of the cleaning tank 12 is 40 l, the circulation pump 45 is driven at a discharge rate of 20 l / min. Along with the driving of the circulation pump 45, the control device 18 activates the temperature adjustment mechanism 46. Based on the control signal from the control device 18, the temperature adjustment mechanism 46 heats the temperature of the cleaning liquid flowing in the supply pipe 41.

  As described above, the temperature of the cleaning liquid (SC1) in the cleaning tank 12 becomes, for example, 40 ° C. at time t2 in FIG.

  Next, as a third step, a predetermined gas is dissolved in the cleaning liquid in the cleaning tank 12 until it is saturated. In other words, the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is increased to the saturated concentration. More specifically, in a state where the irradiation of the ultrasonic wave from the ultrasonic generator 30 is stopped, the gas is supplied into the cleaning tank 12 and the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank 12 is set to the saturated concentration. To rise.

  In the present embodiment, the control device 18 operates the gas supply device 60, and nitrogen from the first gas source 69 a of the gas supply device 60 enters the supply pipe 41 as fine bubbles via the gas supply member 61. Supplied. Similarly, the control device 18 operates the gas supply device 60, and nitrogen is supplied into the supply pipe 41 as fine bubbles from the first gas source 69 a of the gas supply device 60 through the gas supply member 61. Further, the control device 18 keeps the circulation pump 45, the temperature adjustment mechanism 46, and the chemical element supply device 55 operated as they are. Accordingly, during the third step, the cleaning liquid (SC1) is maintained at a temperature within a predetermined range and a concentration within a predetermined range while circulating through the circulation path.

By such an operation, nitrogen and oxygen flow in the supply pipe 41 toward the cleaning tank 12 together with the cleaning liquid. At this time, the cleaning liquid is vigorously stirred in the supply pipe 41 and the cleaning tank 12. Thereby, nitrogen and oxygen become smaller bubbles and mix with the cleaning liquid.
As a result, as shown in FIG. 3, nitrogen and oxygen are rapidly dissolved into the cleaning liquid until the dissolved gas concentration of the cleaning liquid reaches a saturated concentration.

  Here, FIG. 4 shows an example of a change in dissolved gas concentration over time when degassed pure water is left in the atmosphere. In the graph shown in FIG. 4, the vertical axis indicates the dissolved concentration of air dissolved in pure water as a ratio (percentage) to the saturated concentration (for example, 18 ppm) of air dissolved in pure water under the same conditions. FIG. 4 shows a change in dissolved gas concentration when air is continuously supplied into the cleaning tank 12 and a change in dissolved gas concentration when air is not supplied into the cleaning tank. When the gas was not supplied, the air in the atmosphere surrounding the washing tank gradually dissolved, and the dissolved concentration approached the saturation concentration very slowly. On the other hand, when air was supplied into the washing tank 12, the dissolved concentration rapidly increased toward the saturated concentration. In addition, the dissolved concentration could be increased more rapidly by changing the conditions such as the amount of air supplied.

  In the present embodiment shown in Table 1 and FIG. 3, the third step is performed for 120 seconds from time t2 to time t3, and the gas dissolved concentration of the cleaning liquid increases from 0 ppm to the saturated concentration during this time. When the volume of the cleaning tank 12 is 40 l and the discharge amount of the circulation pump 45 is 20 l / min, 120 seconds = 2 minutes is a time during which all the cleaning liquid in the cleaning tank 12 can circulate once. . In particular, according to the present embodiment, the wafer W to be processed is not immersed in the cleaning liquid in the cleaning tank 12 during the third step. Therefore, even if the supply amount of nitrogen and oxygen from the gas supply device 60 is increased, there is no problem that the wafer W is damaged. For this reason, the supply amount of nitrogen and oxygen from the gas supply device 60 can be set appropriately, and the dissolved concentration of the cleaning liquid can be increased to the saturated concentration in a very short time.

  By the way, in this case, whether or not the dissolved gas concentration is “saturated concentration” is determined by using “ppm” as a unit and rounding off with two significant figures. Considering the degree of influence of the dissolved concentration on the particle removal efficiency, the measurement error of the measuring instrument, etc., it is sufficient to make a determination with two significant figures. For example, when the saturation concentration of nitrogen in a certain environment is 16 ppm, if the dissolved concentration of nitrogen in the cleaning liquid is 15.5 ppm or more and less than 16.5 ppm, the dissolved concentration of nitrogen in the cleaning liquid reaches the saturation concentration. In other words, it is treated that nitrogen is dissolved in the cleaning solution until it is saturated.

In the present embodiment, the temperature of the cleaning liquid is increased in the second step.
Then, nitrogen and oxygen are dissolved in the third step with respect to the cleaning liquid whose temperature has risen and whose saturation concentration has decreased. For this reason, in a 3rd process, nitrogen and oxygen can be dissolved to saturation concentration. In other words, if the temperature of the cleaning liquid is adjusted after the gas is dissolved in the cleaning liquid until it is saturated, the saturated concentration changes, so that the dissolved concentration of the cleaning liquid becomes less than or exceeds the saturated concentration (supersaturated) According to the present embodiment, the gas can be dissolved in the cleaning liquid so that the dissolved concentration becomes the saturated concentration after temperature adjustment.

Further, the pressure of the cleaning liquid flowing in the circulation path tends to be higher than the pressure of the cleaning liquid in the cleaning tank 12. If the pressure of the cleaning liquid is different, the saturated concentration of the gas dissolved in the cleaning liquid also changes.
In the present embodiment, the gas supply member 61 is disposed on the downstream side of the filter 47 of the supply pipe 41. That is, nitrogen and oxygen are injected into the cleaning liquid in the supply pipe 41 at a position where the pressure of the cleaning liquid greatly decreases and approaches atmospheric pressure. Therefore, the gas can be dissolved in the cleaning liquid at a dissolved concentration substantially the same as the saturated concentration of the cleaning liquid in the cleaning tank 12 exposed to the atmosphere.

  Next, as a fourth step, the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is adjusted. Specifically, in a state where the gas supply from the gas supply device 60 is stopped, the ultrasonic wave is applied to the cleaning liquid in the cleaning tank 12 from the ultrasonic generator 30, and the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is detected. Reduce. In the present embodiment, during the fourth step, the control device 18 continues to operate the circulation pump 45, the temperature adjustment mechanism 46, and the chemical element supply device 55 as they are. Accordingly, during the third step, the cleaning liquid (SC1) is maintained at a temperature within a predetermined range and a concentration within a predetermined range while circulating through the circulation path.

  When ultrasonic waves are generated in the cleaning liquid, the gas dissolved in the cleaning liquid forms bubbles and floats on the cleaning liquid surface. As a result, the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 decreases. Although the mechanism of such a phenomenon is not necessarily clear, it is estimated that it is as follows. First, when ultrasonic waves are applied to the cleaning liquid, the ultrasonic waves propagate through the cleaning liquid, and pressure fluctuations (pressure vibrations) are generated in the cleaning liquid. Then, the gas dissolved in the cleaning liquid tends to gather in a portion that becomes negative pressure due to generation of ultrasonic waves. For this reason, bubbles are formed in this portion of the cleaning liquid and gradually grow larger, and eventually rise to the surface of the cleaning liquid. As a result, the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 decreases. However, the present invention is not limited to the above estimation mechanism.

  Here, FIG. 5 shows an example of a change in the dissolved gas concentration with the passage of time when the ultrasonic wave is irradiated to the cleaning liquid in which air is dissolved to a substantially saturated concentration. In the graph shown in FIG. 5, the vertical axis represents the dissolved concentration of air dissolved in pure water as a ratio (percentage) to the saturated concentration (for example, 18 ppm) of air dissolved in pure water under the same conditions. FIG. 5 shows changes in dissolved gas concentration when the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves at 700 W, and changes in dissolved gas concentration when the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves at 100 W. ,It is shown. When the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves at 100 W, the gas dissolved in the cleaning liquid is bubbled in an amount larger than the amount of air dissolved in the cleaning liquid under atmospheric pressure. The dissolved gas concentration of the cleaning solution gradually decreased. On the other hand, when the cleaning liquid in the cleaning tank 12 was irradiated with ultrasonic waves at 700 W, air bubbles dissolved in the cleaning liquid became active, and the gas dissolved concentration of the cleaning liquid rapidly decreased. Moreover, the dissolved concentration could be lowered more rapidly by further changing the ultrasonic conditions.

  In the present embodiment shown in Table 1 and FIG. 3, in order to reduce the dissolved gas concentration of the cleaning liquid to a concentration within a desired range in a short time, the cleaning liquid in the cleaning tank 12 is exceeded at a high output (HIGH). Ultrasonic waves are emitted from the sound wave generator 30. Then, the fourth step is performed for 120 seconds from time t3 to time t4, and the gas dissolved concentration of the cleaning liquid decreases from a saturated concentration (for example, 18%) to a concentration of about 80% (for example, 14%) of the saturated concentration during this time. To do. And according to this Embodiment, the wafer W which should be processed in the washing | cleaning liquid in the washing tank 12 is not immersed in the 4th process. Therefore, even if ultrasonic waves are generated from the ultrasonic generator 30 with high output, there is no problem that the wafer is damaged. For this reason, the ultrasonic wave generation output from the ultrasonic wave generator 30 can be set appropriately, and the dissolved concentration of the cleaning liquid can be lowered to a desired concentration in a very short time.

  Next, as a fifth step, the wafer W to be processed is accommodated in the cleaning tank 12 and immersed in the cleaning liquid in the cleaning tank 12. Specifically, the control device 18 drives an elevating mechanism (not shown) connected to the holding member 20. As a result, the holding member 20 holding a predetermined number (for example, 50) of wafers W is lowered, and the wafers W are immersed in the cleaning liquid in the cleaning tank 12. In the present embodiment, during the fifth step, the control device 18 performs both irradiation of ultrasonic waves from the ultrasonic generator 30, supply of cleaning liquid from the cleaning liquid supply device 40, and supply of gas from the gas supply device 60. Stop.

  This step is performed between time t4 and time t5 as shown in FIG. During this process, the atmosphere is dissolved in the cleaning liquid in the cleaning tank 12 exposed to the atmosphere, and the concentration of the cleaning liquid slightly increases. Therefore, the fifth step should be finished within a predetermined time after the end of the fourth step (t4), and ultrasonic cleaning described below should be started.

  Next, as a sixth step, the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves, and the wafer W immersed in the cleaning liquid in the cleaning tank 12 is ultrasonically cleaned. Specifically, the control device 18 operates the ultrasonic generator 30 to irradiate the cleaning liquid in the cleaning tank 12 with ultrasonic waves. As a result, ultrasonic waves are generated in the cleaning liquid in the cleaning tank 12. In the present embodiment, the control device 18 continues operating the circulation pump 45, the temperature adjustment mechanism 46, and the chemical element supply device 55 as they are during the sixth step. Accordingly, during the sixth step, the cleaning liquid (SC1) is maintained at a temperature within a predetermined range and a concentration within a predetermined range while circulating through the circulation path.

  As a result, the wafer W immersed in the cleaning tank 12 is subjected to ultrasonic cleaning (megasonic processing), and particles (dirt etc.) adhering to the surface of the wafer W are removed. . In particular, in the present embodiment, the gas dissolved concentration of the cleaning liquid is adjusted from the saturated concentration to the desired concentration in the fourth step before the ultrasonic cleaning step. Therefore, particles adhering to the surface of the wafer W can be removed with high removal efficiency.

  Here, in FIG. 6, the cleaning liquid is once saturated with air, and then the cleaning liquid is irradiated with ultrasonic waves to lower the dissolved concentration of the cleaning liquid. Thereafter, the wafer W is immersed in the cleaning liquid, and the wafer W is ultrasonically irradiated. The particle removal efficiency of the wafer W in the case of cleaning is shown. The plurality of particle removal efficiencies shown in FIG. 6 are different in that the ultrasonic wave is irradiated to the cleaning liquid to lower the dissolved concentration of the cleaning liquid, and the ultrasonic wave irradiation time is different. It is a measured value for W. In the graph shown in FIG. 6, the horizontal axis indicates the time (minutes) in which the cleaning liquid is irradiated with ultrasonic waves before the wafer is immersed in the cleaning liquid. In the graph shown in FIG. 6, the vertical axis indicates the particle removal efficiency by ultrasonic cleaning. Here, the particle removal efficiency is a ratio (percentage) of the number of particles removed from the wafer W after ultrasonic cleaning among 4000 particles previously attached to the wafer W. That is, the higher the particle removal efficiency, the more particles can be removed from the wafer W.

  As shown in FIG. 6, as the ultrasonic irradiation time becomes longer, the particle removal efficiency gradually increases, but the ultrasonic irradiation time exceeds a certain time (4 minutes in the example of FIG. 6). On the contrary, the particle removal efficiency decreased. That is, the optimum gas dissolved concentration of the cleaning liquid in order to maximize the particle removal efficiency exists in a range larger than 0 ppm and smaller than the saturated concentration. Therefore, particles are removed from the wafer W with extremely high removal efficiency by adjusting the gas dissolved concentration in the above-described fourth step so that the gas dissolved concentration of the cleaning liquid is within the optimum range. Can do.

  The sixth step is performed over 300 seconds from time t5 to time t6 as shown in Table 1 and FIG. Further, during this process, the gas supply from the gas supply device 60 is stopped. Therefore, as in the fourth step, when ultrasonic waves are generated in the cleaning liquid, the gas dissolved in the cleaning liquid forms bubbles and floats on the cleaning liquid surface. As a result, the gas dissolved concentration of the cleaning liquid in the cleaning tank 12 decreases during the sixth step. However, in the sixth step where the ultrasonic irradiation output is small, the dissolved gas concentration gradually decreases compared to the fourth step where the ultrasonic irradiation output is large.

  Next, as a seventh step, the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is increased again to the saturated concentration. That is, the gas is dissolved until it is saturated again with the cleaning liquid in the cleaning tank 12. More specifically, the generation of ultrasonic waves from the ultrasonic generator 30 is stopped, the gas is supplied from the gas supply device 60 into the cleaning tank 12, and the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank 12 is dissolved. To a saturated concentration. As shown in Table 1 and FIG. 3, the seventh step is performed for 30 seconds from time t6 to time t7. During this time, the dissolved gas concentration of the cleaning liquid rises to the saturation concentration.

  In the seventh step, the substrate cleaning apparatus 10 operates in substantially the same manner as the third step described above. For this reason, the detailed description which overlaps with a 3rd process is abbreviate | omitted about a 7th process.

Next, as an eighth step, the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves, and the wafer W immersed in the cleaning liquid in the cleaning tank 12 is ultrasonically cleaned. Specifically, as in the sixth step, the control device 18 operates the ultrasonic generator 30 to irradiate the cleaning liquid in the cleaning tank 12 with ultrasonic waves.
Further, the supply of gas from the gas supply device 60 is stopped. As a result, ultrasonic waves are generated in the cleaning liquid in the cleaning tank 12, and the wafer W is ultrasonically cleaned.

  However, the ultrasonic cleaning conditions in the eighth step differ from the ultrasonic cleaning conditions in the sixth step described above in several points. First, as shown in FIG. 3, the dissolved gas concentration of the cleaning liquid at the start of ultrasonic cleaning is different. Specifically, the gas dissolved concentration of the cleaning liquid is less than the saturated concentration at the start of the sixth step, whereas the gas dissolved concentration of the cleaning liquid is the saturated concentration at the start of the eighth step. Further, as shown in Table 1, the ultrasonic irradiation output by the ultrasonic generator 30 is different. Further, as shown in Table 1, in the sixth step, the cleaning liquid is pumped and circulated to the circulation pump 45, whereas in the eighth step, the driving of the circulation pump 45 is stopped. As described above, since the ultrasonic cleaning conditions are variously different between the sixth step and the eighth step, the ultrasonic propagation mode in the cleaning liquid in the cleaning tank 12 is also greatly different between the sixth step and the eighth step. It becomes like this. As a result, in the sixth step, the region where the particles on the plate surface of the wafer W to be processed are easily removed, and in the eighth step, the region on the plate surface of the wafer W which is processed is easy to remove. , Will be different. Therefore, by performing a plurality of ultrasonic cleaning steps in which the ultrasonic conditions are changed with each other in this manner, particles can be removed from the entire area of the plate surface of the wafer W with high removal efficiency. As a result, not only the particle removal efficiency is increased, but also the particles can be removed uniformly from the entire area of the plate surface of the single wafer W, and the particles are accommodated in the same cleaning tank 12 and processed at the same time. Variations in processing between wafers W can also be suppressed.

  As shown in Table 1 and FIG. 3, the eighth step is performed for 270 seconds from time t7 to time t8. Further, during this process, the gas supply from the gas supply device 60 is stopped. Therefore, as in the fourth and sixth steps, when an ultrasonic wave is generated in the cleaning liquid, the gas dissolved in the cleaning liquid forms bubbles and floats on the cleaning liquid surface. As a result, the gas dissolved concentration of the cleaning liquid in the cleaning tank 12 decreases during the eighth step.

  In the eighth step, the substrate cleaning apparatus 10 operates substantially the same as the sixth step described above, except for the points described above. For this reason, about the 8th process, the detailed description which overlaps with a 6th process is abbreviate | omitted.

Next, as a ninth step, the cleaned wafer W is taken up from the cleaning tank 12. Specifically, the control device 18 drives an elevating mechanism (not shown) connected to the holding member 20.
As a result, the holding member 20 holding a predetermined number (for example, 50) of wafers W rises, and the wafers W are taken up from the cleaning liquid in the cleaning tank 12. The picked-up wafer W is brought into an apparatus to be processed next, for example, a rinse tank for rinsing the wafer W.

  In the present embodiment, during the ninth step, the control device 18 performs both irradiation of ultrasonic waves from the ultrasonic generator 30, supply of cleaning liquid from the cleaning liquid supply device 40, and supply of gas from the gas supply device 60. Stop. As shown in FIG. 3, the ninth step is performed from time t8 to time t9. During this process, the atmosphere is dissolved in the cleaning liquid in the cleaning tank 12 exposed to the atmosphere, and the concentration of the cleaning liquid slightly increases.

  Next, as a tenth step, the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is increased again to the saturated concentration. That is, the gas is dissolved until it is saturated again with the cleaning liquid in the cleaning tank 12. More specifically, the generation of ultrasonic waves from the ultrasonic generator 30 is stopped, gas is supplied into the cleaning tank 12, and the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank 12 is increased to the saturated concentration. Let As shown in Table 1 and FIG. 3, the tenth step is performed for 30 seconds from time t9 to time t10. During this time, the dissolved gas concentration of the cleaning liquid rises to the saturation concentration.

  During the tenth step, the wafer W to be processed is not immersed in the cleaning liquid in the cleaning tank 12. Therefore, even if the supply amount of nitrogen and oxygen from the gas supply device 60 is increased, there is no problem that the wafer is damaged. For this reason, the supply amount of nitrogen and oxygen from the gas supply device 60 can be set appropriately, and the dissolved concentration of the cleaning liquid can be increased to the saturated concentration in a very short time.

  In the tenth step, the substrate cleaning apparatus 10 operates substantially the same as the third step and the seventh step described above. For this reason, the detailed description which overlaps with the 3rd process and the 7th process is omitted about the 10th process.

  As described above, the processing for one lot that is accommodated and processed in the same processing tank 12 at the same time is completed. At the end of the tenth step (time t10), the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is a saturated concentration. Therefore, after that, when processing a lot to be processed next, the above-described fourth to tenth steps may be performed. As a result, the conditions relating to the dissolved gas concentration of the cleaning liquid can be made the same between different lots. Therefore, particles can be removed from the wafers W included in different lots with substantially the same removal efficiency.

  According to the present embodiment as described above, the dissolved concentration of the gas dissolved in the cleaning liquid in which the wafer W is immersed is once increased to the saturation concentration. At this time, the dissolved gas concentration of the cleaning liquid can be quickly brought to a saturated concentration by a simple method. Therefore, when the wafers W of each lot are processed, the conditions relating to the dissolved gas concentration can be quickly aligned by a simple method. As a result, it is possible to suppress variations in particle removal efficiency between lots due to the difference in dissolved gas concentration.

Various modifications can be made to the above-described embodiment within the scope of the present invention.
Hereinafter, an example of a modification will be described.

  In the above-described embodiment, the example in which the gas supply pipe 62 of the gas supply apparatus 60 is connected to the cleaning liquid supply pipe 41 of the cleaning liquid supply apparatus 40 has been described, but the present invention is not limited thereto. For example, as shown in FIG. 7, the gas supply pipe 62 of the gas supply device 60 is connected to the cleaning tank 12, and the gas supply member 61 of the gas supply apparatus 60 supplies gas directly into the cleaning tank W. Good. In the example shown in FIG. 7, the gas supply member 61 can have the same configuration as the cleaning liquid nozzle 42 described above, for example. According to the example shown in FIG. 7, the gas supply member 61 is released into the cleaning liquid in a region close to atmospheric pressure. Therefore, the gas discharged from the gas supply member 61 can be dissolved in the cleaning liquid at a dissolved concentration substantially the same as the saturated concentration of the cleaning liquid in the cleaning tank 12 exposed to the atmosphere.

  In FIG. 7, the same parts as those in the above-described embodiment shown in FIGS. 1 to 6 are denoted by the same reference numerals, and detailed description of the example shown in FIG. 7 overlapping with the above-described embodiment is omitted.

In the above-described embodiment, the process of cleaning the wafer W by ultrasonic cleaning (sixth process and eighth process) is performed twice, and the gas dissolved concentration of the cleaning liquid is set between the two ultrasonic cleaning processes. Although an example in which a step (seventh step) for providing a saturated concentration is shown, the present invention is not limited to this, and the step of setting the gas dissolved concentration of the cleaning liquid performed between two ultrasonic cleaning steps to the saturated concentration is omitted. May be.
Even in such an example, if the conditions other than the dissolved gas concentration of the cleaning liquid are different between the two ultrasonic cleaning steps, particles are uniformly removed from the entire area of the plate surface of the single wafer W. In addition, it is possible to suppress processing variations between wafers W in the same lot.

  Furthermore, in the above-described embodiment, an example in which two ultrasonic cleaning steps with different ultrasonic cleaning conditions are performed has been described, but the present invention is not limited thereto. For example, the ultrasonic treatment process may be performed only once, or the ultrasonic treatment process may be performed three or more times.

Further, in the above-described embodiment, an example in which the step (tenth step) of setting the gas dissolved concentration of the cleaning liquid to the saturated concentration after the wafer is taken up from the cleaning liquid has been shown. It can be omitted. If the cleaning liquid in the cleaning tank 12 is exposed to the atmosphere, the atmosphere gradually dissolves into the cleaning liquid from the liquid surface. That is, if the wafer W of the lot to be processed next is immersed in the cleaning liquid after taking the wafer W for a while, the gas dissolved concentration of the cleaning liquid is expected to recover to the saturated concentration during that time. be able to.
And when the gas dissolved concentration of the cleaning liquid does not recover to the saturated concentration, or only when the gas dissolved concentration of the cleaning liquid is not expected to recover to the saturated concentration, immediately after the wafer W of the previous lot is taken out from the cleaning liquid, or A step of setting the gas dissolved concentration of the cleaning liquid to a saturated concentration may be provided immediately before the wafer W of the next lot is immersed in the cleaning liquid.

  Furthermore, in the above-described embodiment, an example is shown in which the step (third step) of setting the gas dissolved concentration of the cleaning liquid to the saturated concentration is provided before the wafer W is immersed in the cleaning liquid. For example, in the above-described embodiment, when a cleaning liquid saturated with gas at a saturated concentration is sent from the connecting pipe 51 to the supply pipe 41, the dissolved gas concentration of the cleaning liquid stored in the cleaning tank 12 is a saturated concentration, and the wafer It is possible to omit the step of setting the gas dissolved concentration of the cleaning liquid to the saturated concentration before immersing W in the cleaning liquid.

  Further, in the above-described embodiment, in a state where the supply of gas into the cleaning tank 12 is stopped, the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves, and the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is set. Although the example which adjusts was shown, it is not restricted to this, Ultrasonic is irradiated to the cleaning liquid in the cleaning tank 12 while supplying gas into the cleaning tank 12, and the dissolved gas concentration of the cleaning liquid in the cleaning tank 12 is adjusted. You may adjust. As an example, the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves to adjust the dissolved gas concentration of the cleaning liquid in the cleaning tank 12, for example, for a certain period from the start of this process. While supplying the gas into the tank 12, the cleaning liquid in the cleaning tank 12 is irradiated with ultrasonic waves, and thereafter, the ultrasonic wave is applied to the cleaning liquid in the cleaning tank 12 with the supply of gas into the cleaning tank 12 stopped. Then, the gas dissolved concentration of the cleaning liquid in the cleaning tank 12 may be adjusted.

  Further, in the above-described embodiment, an example in which a process of adjusting the gas dissolved concentration of the cleaning liquid by irradiating ultrasonic waves after the gas dissolved concentration of the cleaning liquid is set to a saturated concentration has been shown. The process may be omitted. Even if this step is omitted, variations in particle removal efficiency between lots can be suppressed.

  Furthermore, in various processes in the above-described embodiment, an example in which the cleaning liquid overflowing from the cleaning tank 12 to the outer tank 15 is supplied to the cleaning tank 12 through the return pipe 44 by driving the circulation pump 45 is shown. However, the present invention is not limited to this, and the driving of the circulation pump 45 may be stopped. For example, in the step of cleaning the wafer W by irradiating ultrasonic waves, the supply of the cleaning liquid to the cleaning tank 12 may be stopped.

  Further, in the above-described embodiment, after the cleaned wafer is picked up from the processing tank 12, the wafer (Wa of a different lot) to be processed next is cleaned using the cleaning liquid remaining in the cleaning tank 12. Although the example to do was shown, it is not restricted to this. The cleaning liquid in the cleaning tank 12 may be replaced every time the wafer W to be processed changes. That is, before the wafer W of the lot to be processed next is accommodated in the cleaning tank 12, the cleaning liquid used for cleaning the wafer W of the previous lot is left through the discharge pipe 13. Alternatively, the cleaning tank 12 may be discharged. As a specific example, the steps 1, 2, 3, 4, 5, 6 and 9 described in the above embodiment may be repeatedly performed. At this time, when a cleaning solution having a saturated concentration is supplied to the cleaning tank 12, step 3 can be omitted. Further, Step 2 and Step 4 can be omitted as appropriate. Furthermore, as described above, in step 6, the driving of the circulation pump 45 may be stopped.

  Further, in the above-described embodiment, the example in which the gas supply pipe 60 supplies nitrogen and oxygen into the cleaning liquid and controls the dissolved concentrations of nitrogen and oxygen that occupy most of the air has been described, but the present invention is not limited thereto. . The gas supply device 60 may supply air. Further, the gas supply device 60 may supply one or more gases other than nitrogen and oxygen, and control the dissolved concentration of the gas in the cleaning liquid.

  Furthermore, in the above-described embodiment, the example in which the wafer W is ultrasonically cleaned using SC1 as the cleaning liquid has been described. The wafer W may be ultrasonically cleaned using another chemical solution as the cleaning solution. Further, the wafer W to be processed may be ultrasonically cleaned using pure water as a cleaning liquid.

  Furthermore, although some modified examples of the above-described embodiment have been described, a plurality of modified examples can be applied in appropriate combination.

  Incidentally, as described above, the substrate cleaning apparatus 10 includes the control device 18 including a computer. The control device 18 operates each component of the substrate cleaning apparatus 10 so that the wafer W to be processed is cleaned. The program executed by the computer of the control device 18 in order to perform the cleaning of the wafer W using the substrate cleaning apparatus 10 is also the subject of this case. The recording medium 19 on which the program is recorded is also the subject of this case. Here, the recording medium 19 may be a memory such as a ROM or a RAM, or may be a disk-shaped storage medium such as a hard disk or a CD-ROM.

  In the above description, the substrate cleaning method, the substrate cleaning apparatus, the program, and the recording medium according to the present invention are applied to the cleaning process of the wafer W. However, the present invention is not limited to this, and is not limited to this. It is also possible to apply to cleaning processing of a substrate or the like.

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a substrate cleaning apparatus according to the present invention. 2 is a cross-sectional view of the substrate cleaning apparatus taken along line II-II in FIG. FIG. 3 is a graph showing an example of a change in the dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank in the embodiment of the substrate cleaning method according to the present invention. FIG. 4 is a graph showing an example of a change in the dissolved concentration of the gas dissolved in the cleaning liquid when the degassed cleaning liquid is left in the atmosphere over time. FIG. 5 is a graph showing an example of the change in the dissolved concentration of the gas dissolved in the cleaning liquid when ultrasonic waves are applied to the cleaning liquid in which the gas is dissolved to a substantially saturated concentration. FIG. 6 is a graph showing an example of the relationship between the length of time for irradiating ultrasonic waves and the particle removal efficiency in the step of adjusting the dissolved concentration of the gas dissolved in the cleaning liquid. FIG. 7 is a diagram corresponding to FIG. 1 and illustrating a schematic configuration of a modified example of the substrate cleaning apparatus. FIG. 8 is a graph showing a change in dissolved gas concentration over time when wafers of a plurality of lots are sequentially cleaned by the conventional substrate cleaning method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate cleaning apparatus 12 Cleaning tank 18 Control apparatus 19 Recording medium 20 Holding member 30 Ultrasonic generator 40 Cleaning liquid supply apparatus 41 Supply pipe (cleaning liquid supply pipe)
46 temperature control mechanism 60 gas supply device 61 gas supply member 62 gas supply pipe W wafer

Claims (15)

Irradiating the cleaning liquid stored in the cleaning tank with ultrasonic waves to adjust the dissolved gas concentration of the cleaning liquid in the cleaning tank; and
Immersing the substrate in the cleaning liquid in the cleaning tank in which the gas dissolved concentration is adjusted;
Irradiating the cleaning liquid in the cleaning tank with ultrasonic waves to clean the substrate immersed in the cleaning liquid in the cleaning tank. The substrate according to claim 1, further comprising a step of discharging the cleaning liquid stored in the cleaning tank from the cleaning tank before the substrate to be processed is accommodated in the cleaning tank. Cleaning method. 3. The substrate cleaning method according to claim 1, wherein in the step of cleaning the substrate, the cleaning liquid overflowing from the cleaning tank is circulated and supplied into the cleaning tank. 3. The substrate cleaning method according to claim 1, wherein in the step of cleaning the substrate, the supply of the cleaning liquid into the cleaning tank is stopped. The substrate cleaning method according to claim 1, further comprising a step of adjusting a temperature of the cleaning liquid in the cleaning tank. A cleaning tank capable of accommodating a substrate and storing a cleaning liquid;
An ultrasonic generator for irradiating the cleaning liquid in the cleaning tank with ultrasonic waves;
A supply pipe connected to the cleaning tank and supplying a cleaning liquid into the cleaning tank;
A gas supply pipe connected to the cleaning tank or the supply pipe and supplying gas into the cleaning liquid;
A control device for controlling supply of gas from the gas supply pipe and irradiation of ultrasonic waves by the ultrasonic generator;
The controller is
Before accommodating the substrate in the cleaning tank and immersing the substrate in the cleaning liquid, gas is supplied from the gas supply pipe in a state where the ultrasonic wave irradiation to the cleaning liquid in the cleaning tank by the ultrasonic generator is stopped. The dissolved concentration of the gas dissolved in the cleaning liquid in the cleaning tank is saturated,
After the gas dissolved concentration of the cleaning liquid is saturated, and before the substrate is accommodated in the cleaning tank and immersed in the cleaning liquid, the cleaning liquid in the cleaning tank is irradiated with ultrasonic waves, A substrate cleaning apparatus, wherein gas supply and ultrasonic irradiation are controlled so as to adjust a dissolved gas concentration of the cleaning liquid. The control device irradiates the cleaning liquid in the cleaning tank with ultrasonic waves to clean the substrate immersed in the cleaning liquid in the cleaning tank, and further picks up the cleaned substrate from the cleaning liquid in the cleaning tank. The substrate cleaning apparatus according to claim 6, wherein the gas supply and the ultrasonic irradiation are controlled so that the dissolved gas concentration of the cleaning liquid becomes a saturated concentration. Before immersing the substrate to be processed next in the cleaning liquid in the cleaning tank, the control device irradiates the cleaning liquid in the cleaning tank with ultrasonic waves, and determines the dissolved gas concentration of the cleaning liquid in the cleaning tank. The substrate cleaning apparatus according to claim 7, wherein the supply of gas and the irradiation of ultrasonic waves are controlled so as to adjust. While the control apparatus is irradiating the cleaning liquid in the cleaning tank with ultrasonic waves to clean the substrate immersed in the cleaning liquid in the cleaning tank, the control apparatus transfers the cleaning liquid in the cleaning tank by the ultrasonic generator. 7. The substrate cleaning apparatus according to claim 6, wherein the supply of ultrasonic waves and the irradiation of ultrasonic waves are controlled so as to temporarily stop the irradiation of ultrasonic waves so that the dissolved gas concentration of the cleaning liquid becomes a saturated concentration. A discharge pipe for discharging the cleaning liquid in the cleaning tank;
The control device is configured so that the cleaning liquid stored in the cleaning tank is discharged from the cleaning tank through the drain pipe before the substrate to be processed next is accommodated in the cleaning tank. The substrate cleaning apparatus according to claim 6, wherein the substrate cleaning apparatus is configured . A supply pipe connected to the cleaning tank and supplying a cleaning liquid into the cleaning tank;
11. The substrate cleaning apparatus according to claim 6, wherein the supply pipe is configured to circulate and supply the cleaning liquid overflowing from the cleaning tank into the cleaning tank. 11. A supply pipe connected to the cleaning tank and supplying a cleaning liquid into the cleaning tank;
The supply pipe is configured to stop the supply of the cleaning liquid into the cleaning tank while the cleaning liquid in the cleaning tank is irradiated with ultrasonic waves. The substrate cleaning apparatus according to any one of the above. Further equipped with an adjustment mechanism for adjusting the temperature of the cleaning liquid,
The substrate cleaning apparatus according to claim 6, wherein the control device controls the adjustment mechanism so as to adjust a temperature of a cleaning liquid in the cleaning tank. A recording medium on which a program executed by a control device that controls the substrate cleaning device is recorded,
6. A recording medium that causes a substrate cleaning apparatus to execute the substrate cleaning method according to claim 1 by executing the program by the control device. A program executed by a control device that controls the substrate cleaning apparatus,
A program for causing a substrate cleaning apparatus to execute the method for cleaning a substrate to be processed according to any one of claims 1 to 5, when executed by the control device.

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