JP2006278954A - Substrate treatment method and substrate treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress in-plane uniformity caused by substrate treatment using a treatment liquid. <P>SOLUTION: This method includes a substrate rotating process of rotating one substrate held by a spin chuck, a preceding pure water supply process of supplying pure water on the substrate surface rotated by the substrate rotating process, and a chemicals liquid supply process of supplying a chemical liquid on the substrate surface rotated by the substrate rotating process. The proceeding pure water supply process is started prior to the chemicals liquid supply process, and the proceeding pure water supply process is continued even after the chemicals liquid supply process is started. Later, the proceeding pure water supply process is terminated, then, the chemicals liquid supply process is continued, and then, the chemicals liquid supply process is terminated. The following pure water supply process which supplies the pure water to the substrate surface proceeds from a period before the chemicals liquid supply process is terminated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substrate processing method and a substrate processing apparatus for processing a substrate with a chemical solution and pure water. Substrates to be processed include, for example, semiconductor wafers, glass substrates for liquid crystal display devices, glass substrates for plasma displays, optical disk substrates, magnetic disk substrates, magneto-optical disk substrates, photomask substrates, and the like. .

  In a semiconductor device manufacturing process, a substrate processing apparatus is used to process a semiconductor substrate (wafer). A single-wafer type substrate processing apparatus that processes substrates one by one includes, for example, a spin chuck that rotates while holding the substrate, a chemical nozzle that supplies a chemical toward the substrate held by the spin chuck, and a spin chuck And a pure water nozzle for supplying pure water toward the substrate held on the substrate.

The supply of the chemical solution and pure water from the chemical solution nozzle and the pure water nozzle is generally performed at the timing shown in FIG. That is, after the chemical solution is supplied to the substrate surface for a predetermined time, the supply of the chemical solution is stopped. Thereafter, pure water is supplied to the substrate surface for a predetermined time, and the supply of this pure water is stopped. The chemical solution and pure water supplied to the substrate surface spread outward from the center of rotation by the action of centrifugal force on the substrate and reach the entire surface of the substrate. Thus, after the substrate surface is treated with the chemical solution, the chemical solution on the substrate surface is replaced with pure water.
JP 2005-26489 A

  However, in such substrate processing, there is a problem that non-uniformity of chemical processing occurs in the surface of the substrate. More specifically, for example, when an etching solution such as hydrofluoric acid is used as a chemical solution, the vicinity of the liquid deposition point on the substrate surface (generally the rotation center) In the vicinity), a rapid concentration change occurs, and the etching proceeds rapidly. As a result, non-uniform etching occurs between the vicinity of the landing point and the other region.

At the end of the discharge of the chemical solution, the supply of the etching solution is immediately stopped near the landing point, whereas the etching solution is gradually removed outward from the substrate on the peripheral substrate surface. This also causes variations in etching.
It cannot be expected that the in-plane variation of the etching progress at the start and end of the chemical solution discharge is in a complementary relationship, and in fact, the etching variation is observed on the substrate after processing.

Similar processing non-uniformity occurs when the substrate is processed not only with the etching solution but also with other types of chemicals. This problem is particularly noticeable when a high concentration or high temperature chemical solution having a high processing capability is used.
SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate processing method and a substrate processing apparatus that can suppress in-plane non-uniformity of substrate processing by a processing liquid.

  The invention according to claim 1 for achieving the above object is a single-wafer type substrate processing method for processing substrates (W) one by one, wherein the substrate is held by the substrate holding and rotating mechanism (1). A rotating substrate rotating step, a pure water supplying step for supplying pure water to the surface of the substrate rotated by the substrate rotating step, and a chemical solution for supplying a chemical to the surface of the substrate rotated by the substrate rotating step Including the supplying step, starting the pre-pure water supply step prior to the chemical solution supplying step, and ending the pre-pure water supply step after continuing the pre-pure water supply step even after starting the chemical solution supplying step, Thereafter, the chemical solution supply step is terminated after the chemical solution supply step is continued. The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later. The same applies hereinafter.

  In this method, pure water has been supplied to the surface of the substrate before the chemical solution is supplied to the substrate held and rotated by the substrate holding rotation mechanism, and the supply of this pure water is the chemical solution supply. It will continue after the start. For this reason, the concentration of the chemical solution on the substrate does not change rapidly but gradually increases. After the supply of pure water is stopped, the surface of the substrate is treated only with a chemical solution that has not been diluted with pure water.

  Thus, since the chemical concentration on the substrate at the start of the chemical treatment can be suppressed, the in-plane uniformity of the substrate treatment using the chemical can be improved. In particular, even in the case of using a high-performance chemical solution having a strong processing power such as a high-temperature and / or high-concentration chemical solution, in-plane non-uniformity of the chemical treatment can be suppressed. In other words, the substrate can be processed using a high-temperature and / or high-concentration high-performance chemical without causing in-plane non-uniformity, which can contribute to shortening the substrate processing time. .

  The chemical solution supplied in the chemical solution supply step may be an etching solution. In this case, a uniform etching process can be performed on the substrate surface. Even in the case of using a high-temperature and / or high-concentration high-performance etching solution, in-plane non-uniformity of the etching process can be reduced. An etching process can be performed.

Examples of the etchant include hydrofluoric acid (oxide or nitride etchant), hydrofluoric acid (silicon etchant), alkaline solution such as potassium hydroxide (silicon etchant), and phosphoric acid (silicon nitride etchant). Etching solution) can be exemplified.
The pre-pure water supply step and the chemical solution supply step may be performed using a pure water nozzle that supplies pure water to a substrate held by the substrate holding rotation mechanism and a chemical solution nozzle that supplies chemical solution, respectively. Further, a processing liquid nozzle for supplying a processing liquid toward the substrate held by the substrate holding rotation mechanism is provided, and by supplying the chemical liquid and / or pure water in common to the processing liquid nozzle, A pre-pure water supply step and a chemical solution supply step may be performed.

Further, the processing liquid may be supplied to both sides of the substrate. Specifically, for example, when the substrate holding and rotating mechanism rotates the substrate while holding the substrate substantially horizontal, pure water and / or a chemical solution may be supplied to both the upper and lower surfaces of the substrate. Good.
According to a second aspect of the present invention, in the pre-pure water supply step, the supply flow rate of pure water to the substrate is gradually reduced at the end of the pre-pure water supply step (preferably after the start of the chemical solution supply step). The substrate processing method according to claim 1, further comprising a step of gradually decreasing the pure water flow rate (B 1).

According to the present invention, since the supply flow rate of pure water is gradually reduced at the end of the previous pure water supply step, the concentration of the chemical solution on the substrate can be gradually increased after the supply of the chemical solution is started. Thereby, since the change of the chemical concentration on the substrate can be further slowed down, more uniform chemical processing can be performed.
According to a third aspect of the present invention, in the chemical solution supply step, the chemical solution flow rate for gradually increasing the supply flow rate of the chemical solution to the substrate in the initial stage of the chemical solution supply step (preferably before the completion of the pre-deionized water supply step). 3. The substrate processing method according to claim 1, further comprising a gradual increase step (A1).

In this method, since the chemical supply flow rate is gradually increased in the initial stage of the chemical supply process, the mixing ratio of the chemical supplied to the substrate and pure water gradually changes, and the concentration of the chemical increases gradually on the substrate. It will be. As a result, since the concentration change of the chemical solution on the substrate can be further moderated, the in-plane uniformity of the chemical treatment can be further improved.
According to a fourth aspect of the present invention, pure water is supplied to the surface of the substrate which is started after the pre-pure water supply step and before the chemical solution supply step and is rotated by the substrate rotation step. The substrate processing method according to claim 1, further comprising a post-pure water supply step.

  In this method, the supply of pure water to the substrate surface can be started before the end of the supply of the chemical solution. Thereby, the concentration of the chemical solution on the substrate (especially the concentration of the chemical solution at the landing point) can be gradually decreased at the end of the chemical solution supply step. As a result, in-plane non-uniformity in processing due to a sudden change in the chemical concentration at the end of the chemical supply step can be suppressed. Then, by continuing the supply of pure water after the chemical solution supply step, it is possible to perform a rinsing process that replaces the chemical solution on the substrate surface with pure water.

According to a fifth aspect of the present invention, in the post-pure water supply step, the supply flow rate of pure water to the substrate is gradually increased in the initial stage of the post-pure water supply step (preferably, before the end of the chemical solution supply step). 5. The substrate processing method according to claim 4, further comprising a step of gradually increasing the pure water flow rate (B2).
By this method, the concentration of the chemical solution on the substrate (especially the concentration of the chemical solution at the landing point) is gradually reduced at the end of the chemical solution supply step. Thereby, the change of the chemical concentration on the substrate can be further slowed down, and more uniform chemical processing can be performed.

According to a sixth aspect of the present invention, in the chemical solution supply step, the chemical solution flow rate is gradually reduced at the end of the chemical solution supply step (preferably after the start of the post pure water supply step). 6. The substrate processing method according to claim 4, further comprising a step (A2).
In this method, by gradually decreasing the chemical supply amount at the end of the chemical supply process, the mixing ratio of the chemical and pure water gradually changes, and as a result, the concentration of the chemical on the substrate gradually decreases. . Thereby, since the change of the chemical concentration on the substrate can be further moderated, the chemical treatment with improved in-plane uniformity is realized.

  The invention described in claim 7 is a substrate holding and rotating mechanism (1) for holding and rotating one substrate (W), and pure water for supplying pure water to the surface of the substrate held by the substrate holding and rotating mechanism. Supply mechanism (2, 17, 18; 4, 15, 26, 27) and chemical supply mechanism (3, 5, 19, 20; 4, for supplying chemical to the surface of the substrate held by the substrate holding and rotating mechanism. 15, 28, 29), and the pure water supply mechanism and the chemical solution supply mechanism are controlled so that pure water is supplied to the surface of the substrate by the pure water supply mechanism before starting the chemical solution supply by the chemical solution supply mechanism, and the chemical solution Control means (30) for continuing the supply of pure water by the pure water supply mechanism even after starting the supply of the chemical solution by the supply mechanism, and thereafter stopping the supply of pure water by the pure water supply mechanism. A substrate processing apparatus characterized by

With this configuration, it is possible to suppress a sudden change in the concentration of the chemical solution on the substrate surface (particularly, the concentration of the chemical solution at the landing point) at the start of the supply of the chemical solution by the chemical solution supply mechanism. As a result, chemical treatment with improved in-plane uniformity can be realized.
In addition, since a rapid change in the concentration of the chemical solution on the substrate at the start of the supply of the chemical solution can be suppressed, in-plane non-uniformity of processing can be suppressed even when a high temperature and / or high concentration chemical solution is used. This makes it possible to shorten the time required for substrate processing using a high-temperature and / or high-concentration chemical solution.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram schematically showing the configuration of a substrate processing apparatus according to an embodiment of the present invention. The substrate processing apparatus is a single-wafer type substrate processing apparatus that processes substrates one by one. The spin chuck 1 that holds the substrate W substantially horizontally and rotates around the vertical axis, and the spin chuck 1 hold the substrate W. A pure water nozzle 2 for supplying pure water toward the rotation center of the substrate W being rotated, and a chemical solution (for example, etching) having a constant concentration toward the rotation center of the substrate W held and rotated by the spin chuck 1. And a chemical nozzle 3 for supplying a liquid). The substrate processing apparatus further includes a lower surface processing liquid nozzle 4 that supplies a processing liquid toward the center of the lower surface of the substrate W that is held and rotated by the spin chuck 1.

  The spin chuck 1 includes a disk-shaped spin base 11, a plurality of chuck pins 12 that are erected on the spin base 11 and sandwich the substrate W, and a rotary shaft 13 that supports the spin base 11 substantially horizontally. And a rotation drive mechanism (for example, including a motor) 14 for applying a rotational force to the rotation shaft 13. The rotary shaft 13 is a hollow shaft arranged along the vertical direction, and a processing liquid supply pipe 15 is inserted through the rotary shaft 13. The tip of the processing liquid supply pipe 15 forms the lower surface processing liquid nozzle 4 that penetrates the spin base 11 and faces the center of the lower surface of the substrate W held by the spin chuck 1.

  Pure water (deionized water) is supplied to the pure water nozzle 2 via a pure water supply path 17 connected to a pure water supply source. The pure water supply path 17 is provided with a pure water valve 18 for switching between supply / stop of pure water. The chemical liquid from the chemical liquid supply source 5 is supplied to the chemical liquid nozzle 3 through the chemical liquid supply path 19. The chemical solution supply path 19 is provided with a chemical solution valve 20 for switching supply / stop of the chemical solution. The chemical liquid supply source 5 includes a chemical liquid tank 6 that stores a chemical liquid having a substantially constant concentration, a pump 7 that draws the chemical liquid from the chemical liquid tank 6 and sends it to the chemical liquid supply path 19, and a foreign substance in the chemical liquid to be delivered. And a temperature adjusting unit 9 for adjusting the temperature of the chemical solution to be delivered.

  On the other hand, a treatment liquid mixing unit 25 is coupled to the treatment liquid supply pipe 15. The treatment liquid mixing unit 25 is supplied with pure water from a pure water supply source via a pure water supply path 26. The pure water supply passage 26 is provided with a pure water valve 27 for switching between supply / stop of pure water. Further, the chemical liquid from the chemical liquid supply source 5 is supplied to the treatment liquid mixing unit 25 via the chemical liquid supply path 28. The chemical liquid is switched to supply / stop of the chemical liquid to the chemical liquid supply path 28. A valve 29 is interposed.

The operation of the rotary drive mechanism 14 and the pump 7 and the opening and closing of the pure water valves 18 and 27 and the chemical liquid valves 20 and 29 are controlled by the control device 30.
FIG. 2 is a diagram for explaining a substrate processing process by the substrate processing apparatus. FIG. 2A shows a change over time in the supply flow rate of the chemical solution supplied from the chemical solution nozzle 3 to the upper surface of the substrate W. FIG. 2 (b) shows the change over time of the supply flow rate of pure water supplied from the pure water nozzle 2 to the upper surface of the substrate W, and FIG. 2 (c) shows the rotation speed of the spin chuck 1 (that is, the rotation speed of the substrate W). ).

  As shown in FIG. 2, the substrate processing step includes a chemical solution supplying step for supplying a chemical solution to the substrate W, a pre-pure water supply step for starting supply of pure water to the substrate W prior to the chemical solution supplying step, and a chemical solution supplying step. And a post-pure water supply step of starting the supply of pure water to the substrate W from the end of the process and continuing the supply of pure water after the chemical solution supply step. During the period in which these steps are performed, as shown in FIG. 2 (c), the substrate W is rotated by the rotation of the spin chuck 1, and pure water and a chemical solution are applied to the substrate W in the rotated state. Will be supplied.

  More specifically, when an unprocessed substrate W is delivered to the spin chuck 1 by a substrate transport robot (not shown), the control device 30 controls the rotation drive mechanism 14 to rotate the spin chuck 1. The rotational speed of the substrate W is accelerated to the liquid processing rotational speed. Thereafter, the control device 30 opens the pure water valve 18 and starts the pre-pure water supply process. Thereby, on the upper surface of the substrate W rotated by being held by the spin chuck 1, the pure water that has received the centrifugal force spreads outward from the center of rotation and spreads over the entire upper surface of the substrate W. After the start of such a pre-deionized water supply process, the control device 30 opens the chemical liquid valve 20 and starts the chemical liquid supply process. At this time, the pure water valve 18 remains open, and both the pure water and the chemical solution are supplied onto the substrate W. Therefore, even immediately after the chemical liquid valve 20 is opened and the chemical liquid supply from the chemical liquid nozzle 3 is started, the concentration of the chemical liquid on the surface of the substrate W (particularly, near the liquid landing point near the rotation center) does not rapidly increase. Shows slow changes.

Thereafter, when a certain time has elapsed, the control device 30 closes the pure water valve 18 and ends the previous pure water supply step. After that, the control device 30 keeps the chemical liquid valve 20 in the open state and continues the chemical liquid supply process. Thus, the surface of the substrate W is treated with the chemical solution for a certain time.
At the end of the chemical solution supply process, the control device 30 opens the pure water valve 18 and starts the pure water supply process after a certain time before closing the chemical solution valve 20. As a result, a sudden change in the concentration of the chemical on the substrate W (especially the concentration of the chemical near the landing point near the rotation center) is suppressed, and the chemical concentration decreases while showing a gradual change. Even after the chemical liquid valve 20 is closed and the chemical liquid supply process is completed, the control device 30 keeps the pure water valve 18 open for a certain period of time. As a result, the chemical solution on the substrate W is replaced with pure water, and so-called rinse treatment is performed.

Thereafter, the control device 30 closes the pure water valve 18 to complete the post-pure water supply step, and then controls the rotation drive mechanism 14 to accelerate the rotation speed of the spin chuck 1 and rotate the substrate W. The speed is the drying rotation speed. Thereby, the water on the substrate W is shaken off by the centrifugal force, and the surface of the substrate W is dried.
The control device 30 performs the same control for the lower surface processing liquid nozzle 4 that supplies the processing liquid to the lower surface of the substrate W. That is, the same control as that for the chemical liquid valve 20 and the pure water valve 18 is performed on the chemical liquid valve 29 and the pure water valve 27. However, on the lower surface side of the substrate W, the chemical liquid is not mixed on the substrate surface (lower surface), but the chemical liquid and pure water are mixed in the processing liquid mixing unit 25, and the mixed processing liquid is the processing liquid. The liquid is discharged from the lower surface treatment liquid nozzle 4 toward the rotation center of the lower surface of the substrate W through the supply pipe 15. Of course, the chemical solution and the pure water are mixed for a certain period of time in the initial and final stages of the chemical solution supply process, and during the other periods, only pure water or only the chemical solution is transferred from the lower surface treatment liquid nozzle 4 to the lower surface of the substrate W. It is discharged toward the center. The processing liquid discharged to the center of the lower surface of the substrate W receives the centrifugal force, spreads outward, and is supplied to the entire lower surface of the substrate W.

  As described above, according to this embodiment, the pre-pure water supply process overlaps in time at the beginning of the chemical solution supply process, and the post-pure water supply process overlaps in time at the end of the chemical solution supply process. is doing. Thereby, it is possible to suppress a sudden change in the concentration of the chemical solution on the substrate W when the supply of the chemical solution is started and when the supply of the chemical solution is stopped. As a result, since the rapid change of the chemical concentration at the liquid landing point on the surface of the substrate W can be suppressed, the in-plane uniformity of the chemical processing can be remarkably improved.

In addition, even when a high-performance and / or high-concentration chemical solution is used, sudden changes in the concentration of the chemical solution on the substrate W can be suppressed. By using such a high-performance chemical solution, the substrate processing time can be shortened, In addition, in-plane non-uniformity of substrate processing can be suppressed. Thereby, the time required for the substrate processing can be shortened without deteriorating the quality of the substrate processing.
In particular, when an etching solution is used as the chemical solution, a highly uniform etching process can be performed even when a high-performance and / or high-concentration high-performance etching solution is used.

  As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form. For example, as shown by a two-dot chain line in FIG. 2 (a), a chemical liquid flow rate increasing step A1 for gradually increasing the chemical liquid supply flow rate at the start of supply of the chemical liquid (particularly during the period before the end of the previous pure water supply process) When the supply of the chemical solution is stopped (particularly during the period after the start of the post-pure water supply step), the chemical solution flow rate gradually decreasing step A2 for gradually decreasing the chemical solution supply flow rate may be performed. More specifically, a valve with a flow rate adjusting function is used as the chemical liquid valve 20, and the opening degree of the chemical liquid valve 20 is gradually increased / decreased when the chemical liquid supply is started and / or when the chemical liquid supply is stopped by the control device 30. That's fine. In this way, fluctuations in the chemical concentration on the substrate W can be made more gradual, so that substrate processing with higher uniformity can be performed. The same applies to the processing on the lower surface side of the substrate W. A valve with a flow rate adjusting function is used as the chemical valve 29, and the opening degree of the chemical valve 29 is controlled by the control device 30 at the time of starting and / or stopping the supply of the chemical liquid. What is necessary is just to make it increase / decrease gradually.

  Further, as shown by a two-dot chain line in FIG. 2 (b), a pure water flow gradual reduction process B1 for gradually decreasing the pure water supply flow rate at the end of the previous pure water supply process (especially the period after the start of the chemical solution supply process) is performed. Alternatively, a pure water flow gradual increase step B2 for gradually increasing the pure water supply flow rate may be performed at an initial stage of the post-pure water supply step (particularly, a period before the end of the chemical solution supply step). More specifically, a valve with a flow rate adjusting function is used as the pure water valve 18, and the opening degree of the pure water valve 18 is gradually decreased by the control device 30 at the end of the pre-pure water supply process. The opening degree of the pure water valve 18 may be gradually increased by the control device 30 during the initial period of the pure water supply process. In this way, since the change in the chemical concentration on the substrate W can be made more gradual, the in-plane uniformity of substrate processing can be further improved.

Of course, if the gradual change in the chemical supply flow rate and the gradual change in the pure water supply flow rate are used together, the chemical concentration on the substrate W can be changed more slowly. The internal uniformity can be further improved.
Further, in the initial and final stages of the chemical liquid supply process, the chemical liquid supply may be intermittently performed to perform the chemical liquid flow rate gradually increasing process and the chemical liquid flow rate gradually decreasing process as described above. More specifically, the chemical solution 20 is intermittently supplied by intermittently opening the chemical solution valve 20 or by using the pulsation of a pump 7 (for example, comprising a diaphragm pump) that sends out the chemical solution from the chemical solution tank 6. May be. This suppresses the chemical supply flow rate at the initial stage and the final stage of the chemical supply process, so that the fluctuation of the chemical concentration on the substrate W can be slowed down, which contributes to in-plane uniformity of substrate processing.

Further, the post-pure water supply process does not necessarily have to overlap in time with the end of the chemical supply process. Even in this case, since the pre-pure water supply process overlaps with time in the early stage of the chemical solution supply process, it is possible to suppress a sudden change in the concentration of the chemical solution at the start of the supply of the chemical solution. Inner uniformity can be improved.
In addition, various design changes can be made within the scope of matters described in the claims.

1 is a conceptual diagram schematically showing the configuration of a substrate processing apparatus according to an embodiment of the present invention. It is a diagram for explaining a substrate processing step by the substrate processing apparatus, (a) shows a time change of the chemical supply flow rate, (b) shows a time change of the pure water supply flow rate, (c) is. The time change of the rotation speed of the substrate is shown. It is a time chart for demonstrating a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spin chuck 2 Pure water nozzle 3 Chemical liquid nozzle 4 Lower surface processing liquid nozzle 5 Chemical liquid supply source 6 Chemical liquid tank 7 Pump 8 Filter 9 Temperature control unit 11 Spin base 12 Chuck pin 13 Rotating shaft 14 Rotation drive mechanism 15 Processing liquid supply pipe 17 Pure Water supply path 18 Pure water valve 19 Chemical liquid supply path 20 Chemical liquid valve 25 Treatment liquid mixing unit 26 Pure water supply path 27 Pure water valve 28 Chemical liquid supply path 29 Chemical liquid valve 30 Control device A1 Chemical liquid flow gradual increase process A2 Chemical liquid flow gradual decrease process B1 Pure Water flow gradually decreasing process B2 Pure water flow gradually increasing process W Substrate

Claims (7)

A single wafer processing method for processing substrates one by one,
A substrate rotating step of holding and rotating the substrate by the substrate holding and rotating mechanism;
A pure water supplying step for supplying pure water to the surface of the substrate rotated by the substrate rotating step;
A chemical solution supplying step of supplying a chemical solution to the surface of the substrate rotated by the substrate rotating step,
Prior to the chemical solution supply step, the pre-pure water supply step is started, and the pre-pure water supply step is terminated after the pre-pure water supply step is continued even after the chemical solution supply step is started. The substrate processing method is characterized in that the chemical solution supplying step is terminated after the process is continued.   The pre-pure water supply step includes a pure water flow gradual reduction step of gradually decreasing the supply flow rate of pure water to the substrate (after the start of the chemical solution supply step) at the end of the pre-pure water supply step. The substrate processing method according to claim 1.   The chemical solution supply step includes a chemical solution flow rate increasing step of gradually increasing the supply flow rate of the chemical solution to the substrate (before the completion of the pre-deionized water supply step) at an early stage of the chemical solution supply step. Item 3. A substrate processing method according to Item 1 or 2.   It further includes a post-pure water supply step that supplies pure water to the surface of the substrate rotated after the pre-pure water supply step and before the end of the chemical solution supply step and rotated by the substrate rotation step. The substrate processing method according to claim 1, wherein:   The post-pure water supply step includes a pure water flow gradual increase step that gradually increases the supply flow rate of pure water to the substrate (before the chemical solution supply step) at the initial stage of the post-pure water supply step. The substrate processing method according to claim 4, wherein:   The chemical liquid supply step includes a chemical liquid flow rate gradually decreasing step of gradually decreasing the chemical liquid supply flow rate to the substrate (after the start of the post pure water supply step) at the end of the chemical liquid supply step. 6. The substrate processing method according to 4 or 5. A substrate holding and rotating mechanism for holding and rotating one substrate;
A pure water supply mechanism for supplying pure water to the surface of the substrate held by the substrate holding rotation mechanism;
A chemical supply mechanism for supplying a chemical to the surface of the substrate held by the substrate holding rotation mechanism;
The pure water supply mechanism and the chemical solution supply mechanism are controlled so that pure water is supplied to the surface of the substrate by the pure water supply mechanism before the chemical solution supply starts by the chemical solution supply mechanism, and the supply of the chemical solution by the chemical solution supply mechanism is started. A substrate processing apparatus comprising: control means for continuing the supply of pure water by the pure water supply mechanism after stopping the supply, and thereafter stopping the supply of pure water by the pure water supply mechanism.

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