JPWO2018037691A1 - Coating method, coating apparatus and storage medium - Google Patents

Abstract

An object of the present invention is to remove particles in a short time when applying a coating solution to a wafer to more reliably suppress defects in the coating film. SOLUTION: Before supplying a coating liquid 102 to a wafer W carried into a coating apparatus, first, a thinner 100 is supplied to wet the surface of the wafer W, and then the surface of the wafer W is dried. As a result, the particles 101 on the surface of the wafer W can easily flow. Further, when the surface of the wafer W is subsequently supplied with the thinner 100 by drying the surface of the wafer W, the cross section of the gas-liquid interface of the liquid pool of the thinner becomes round, and the particles 101 can be pushed with a large force. The particles 101 can be removed more reliably in a short time. Therefore, when the coating liquid 102 is applied to the wafer W thereafter, formation of comet spots on the SOC film due to the adhesion of the particles 101 can be suppressed. [Selected figure] Figure 2

Description

  The present invention relates to a technology for supplying a coating solution to the surface of a substrate to form a coating film.

  As one of the semiconductor manufacturing processes, a coating solution is supplied to a semiconductor wafer (hereinafter referred to as a “wafer”), and a coating film such as a resist film, an antireflective film, or an SOC (Spin On) mainly composed of carbon serving as an etching mask. Cap) There is a formation process such as a film. In this process, spin coating is widely used.

  For example, an etching mask such as an SOC film is formed so as to cover the surface of the wafer after forming a step pattern on the wafer, but particles generated in a previous step such as an etching process for forming the step pattern on the wafer are It may adhere to the surface of the wafer. Thereafter, when the coating solution is supplied to the wafer to perform spin coating, the particles inhibit the spread of the coating solution, and comet-type mottles (comet spots) may be formed on the coating film with the particles as nuclei. Since semiconductor devices tend to be miniaturized more and more, such defects in the coating film cause a reduction in yield.

  As a countermeasure against such coating defects, for example, as described in Patent Document 1, a thinner is supplied to the wafer before the coating solution is applied to clean the surface to remove particles. From the viewpoint of maintaining the throughput, there has been a demand to remove particles efficiently in a shorter time. In addition, in order to avoid an increase in the size of the apparatus, it has been required to clean particles in a module that performs coating.

JP, 2006-208456, A

  The present invention has been made under the circumstances described above, and its object is to remove particles in a short time and apply a coating film to a substrate by forming a coating film by removing a particle in a short time. It is about providing the technology which can be suppressed.

The coating method of the present invention comprises the steps of: holding the substrate horizontally;
Next, the entire surface of the substrate is wetted with a processing solution,
And then rotating the substrate about a vertical axis to dry the surface of the substrate;
Supplying a cleaning solution to the surface of the substrate while rotating the substrate around a vertical axis;
And then supplying a coating solution to the surface of the substrate to form a coating film.

  The storage medium of the present invention is a storage medium storing a computer program used for a coating apparatus which supplies a coating solution to a substrate which is held horizontally and rotated about a vertical axis and is coated. It is characterized in that a step group is configured to execute.

The coating apparatus of the present invention comprises a substrate holder for holding the substrate horizontally;
A rotation mechanism for rotating the substrate holding unit around a vertical axis;
A coating solution nozzle for supplying a coating solution to the substrate held by the substrate holding unit;
A treatment liquid nozzle for supplying a treatment liquid to the substrate held by the substrate holding unit;
A cleaning solution nozzle for supplying a cleaning solution to the substrate held by the substrate holding unit;
Holding the substrate horizontally, then wetting the entire surface of the substrate with a treatment solution, and then rotating the substrate about a vertical axis to dry the surface of the substrate, and then rotating the substrate about the vertical axis And a controller for performing a step of supplying a cleaning solution to the surface of the substrate while rotating the substrate, and a step of forming a coating film by supplying a coating solution to the surface of the substrate thereafter.

According to the present invention, the processing liquid is supplied to the substrate to wet the surface of the substrate before the coating liquid is supplied to the substrate, and then the surface of the substrate is dried. This makes it easy for the particles to detach from the surface of the substrate. Further, by drying the surface of the substrate, the particles can be pushed with a large force by the gas-liquid interface when the cleaning liquid is continuously supplied to the surface of the substrate, and the particles can be removed more reliably in a short time. Therefore, when the coating liquid is applied to the substrate thereafter, the formation of mottles on the coating film due to the adhesion of particles can be suppressed.
Further, according to the coating apparatus of the present invention, since the substrate has a cleaning function, it is not necessary to separately provide a cleaning apparatus.

1 is a cross-sectional view of an SOC film coating apparatus according to an embodiment of the present invention. FIG. 8 is an explanatory view in which a time chart of the number of rotations of a wafer is associated with a processing step. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. It is explanatory drawing explaining the effect | action of embodiment of this invention. FIG. 6 is a characteristic diagram showing the removal rate of PSL particles in verification test 1; FIG. 10 is a characteristic diagram showing the removal rate of PSL particles in verification test 2; FIG. 10 is a characteristic diagram showing the removal rate of PSL particles in verification test 3; FIG. 10 is a characteristic diagram showing the removal rate of PSL particles in verification test 3; FIG. 10 is a characteristic diagram showing the removal rate of PSL particles in verification test 3; FIG. 10 is a characteristic diagram showing the removal rate of PSL particles in verification test 3; FIG. 10 is a characteristic diagram showing the removal rate of PSL particles in verification test 4;

  As an example of a coating apparatus according to the embodiment of the present invention, a coating apparatus for forming an SOC film on a wafer W will be described with reference to FIG. The coating apparatus includes a cup module 1, and the cup module 1 includes a spin chuck 11 which is a substrate holding unit that sucks and holds horizontally the central portion of the back surface of the wafer W. The spin chuck 11 is connected to the rotation mechanism 13 from below via the shaft 12 and can be rotated about the vertical axis by the rotation mechanism 13.

  A circular plate 14 is provided on the lower side of the spin chuck 11 so as to surround the shaft 12 with a gap. Further, in the circular plate 14, three through holes 17 are formed at equal intervals in the circumferential direction, and elevating pins 15 are provided in each through hole 17. The lift pins 15 are configured to be lifted and lowered by the lift mechanism 16, and the wafer W is delivered between the transfer arm outside the coating apparatus and the spin chuck 11 by lifting and lowering the lift pins 15.

  Further, a cup body 2 is provided so as to surround the spin chuck 11. The cup body 2 receives the waste liquid scattered or spilled from the rotating wafer W, and discharges the waste liquid out of the coating apparatus. The cup body 2 is provided with a mountain-shaped guide portion 21 provided in a ring shape having a mountain-shaped cross section around the circular plate 14, and an annular vertical wall extending downward from the outer peripheral end of the mountain-shaped guide portion 21. 23 are provided. The chevron guide portion 21 guides the liquid spilled from the wafer W to the outer lower side of the wafer W.

Further, a vertical cylindrical portion 22 is provided so as to surround the outside of the mountain-shaped guide portion 21, and an upper guide portion 24 obliquely extending inward and upward from the upper edge of the cylindrical portion 22. The upper guide portion 24 is provided with a plurality of openings 25 in the circumferential direction. Further, on the lower side of the cylindrical portion 22, a ring-shaped liquid receiving portion 26 having a concaved cross section is formed below the mountain-shaped guide portion 21 and the vertical wall 23. In the liquid receiving portion 26, the drainage passage 27 is connected to the outer peripheral side, and an exhaust pipe 28 is provided on the inner peripheral side of the drainage passage 27 so as to project from below.
Further, a cylindrical portion 29 is provided so as to extend upward from the base end side peripheral edge of the upper guide portion 24, and an inclined wall 30 is provided so as to extend inwardly and upward from the upper edge of the cylindrical portion 29. The liquid scattered by the rotation of the wafer W is received by the cylindrical portion 29, the inclined wall 30, the upper guide portion 24 and the vertical wall 23 and introduced into the drainage path 27.

The coating apparatus includes a coating solution nozzle 3 for supplying a coating solution in which an organic material to be a precursor of an SOC film is dissolved in a solvent to a wafer W. The coating solution nozzle 3 is connected to a coating solution supply mechanism 32 via a coating solution supply pipe 31. As a coating liquid, a liquid in which a polymer material having a skeleton of an organic material containing a carbon compound, for example, a polyethylene structure ((-CH _2- ) _n ) is dissolved in a solvent is used.

The coating apparatus includes a thinner nozzle 4 for supplying a thinner is a solvent which also serves as a cleaning liquid and the treatment liquid, and N ₂ gas nozzle 5 for supplying nitrogen gas (N ₂ gas) to the wafer W, is provided The nozzle unit 6 is provided. The thinner nozzle 4 is connected to a thinner supply mechanism 42 via a thinner supply pipe 41. The thinner supply mechanism 42 includes, for example, devices such as a pump, a valve, and a filter, and is configured to discharge a predetermined amount of thinner from the tip of the thinner nozzle 4. Further, the N ₂ gas nozzle 5 is connected to the N ₂ gas supply mechanism 52 via the N ₂ gas supply pipe 51. N ₂ gas supply mechanism 52, for example pumps, valves, provided with a device such as a filter, is configured to eject the N ₂ gas from the N ₂ gas nozzle 5.
The coating solution nozzle 3 and the nozzle unit 6 are configured to move between a central upper portion of the wafer W and a standby position outside the cup 2 by moving mechanisms (not shown).

The application device is provided with a control unit 10 which is, for example, a computer. The control unit 10 has a program storage unit, and in the program storage unit, delivery of the wafer W between an external transfer arm and the spin chuck 11, rotation of the spin chuck 11, coating liquid, thinner A program is stored in which an instruction is set to execute the N ₂ gas supply sequence. The program is stored in a storage medium such as, for example, a flexible disk, a compact disk, a hard disk, an MO (magneto-optical disk), or a memory card, and installed in the control unit 10.

Subsequently, the operation of the embodiment of the present invention will be described with reference to the time chart of FIG. 2 and the operation diagrams of FIGS. The above-described wafer W is delivered to the spin chuck 11 by the cooperative action of an external transfer arm (not shown) and the lift pins 15.
First, as shown in FIG. 2A, the wafer W is rotated at a rotational speed of, for example, 2000 rpm for 1 second from time t0, as shown in FIG. 2A. Further, as shown in FIG. 3, the nozzle unit 6 is moved from the standby position, and the thinner nozzle 4 is moved toward the center of the wafer W to a position for discharging the thinner which is the processing liquid.

  Next, as shown in FIG. 2A, the rotation number of the wafer W is lowered at time t1 and maintained at 1000 rpm, and the thinner 100 is moved to time t1 toward the wafer W as shown in FIGS. The discharge is performed at a flow rate of, for example, 75 sccm for 3 seconds from time t2 to time t2. As a result, the thinner 100 spreads to the surface of the wafer W by the centrifugal force, and the entire surface of the wafer W becomes wet.

Subsequently, as shown in FIG. 2A, the number of revolutions of the wafer W is increased at time t2 and maintained at 3000 rpm, and the nozzle unit 6 is moved as shown in FIGS. _{The 2} gas nozzle 5 is moved toward the center of the wafer W to a position where the gas is discharged, and the N ₂ gas is discharged. Here, the time from time t2 to time t3 is 3 seconds. In the previous step, the wafer W is in a wet state by the thinner 100, but the number of rotations of the wafer W is increased, and the thinner 100 is shaken off by supplying N ₂ gas toward the surface of the wafer W. The surface of the wafer W is dried.

Before the supply of the thinner 100, water is adsorbed on the surface of the wafer W. The particles adhere to the surface of the wafer W, but microscopically, it is considered to be in a state of being adsorbed by the surface moisture of the wafer W. Therefore, in this example, when the thinner 100 is supplied to the central portion of the rotating wafer W to spread the thinner, the moisture adsorbed on the surface of the wafer W is washed away by the thinner 100. Further, by increasing the rotational speed of the wafer W to shake off the thinner 100 and blowing the N ₂ gas to dry the surface of the wafer W, the particles adhering to the surface of the wafer W become easy to move. The thinner 100 supplied at time t1 is a processing liquid that is a liquid for removing moisture on the surface of the wafer W, but particles adhering to the surface of the wafer W due to spreading due to the rotation of the wafer W It can be said that it is a washing solution because it plays a role of washing away a portion of the

Thereafter, the discharge of the N ₂ gas is stopped, and the nozzle unit 6 is moved to move the thinner nozzle 4 toward the center of the wafer W to a position where the thinner 100 as the cleaning liquid is discharged. Then, as shown in FIG. 2B and FIG. 6, the rotation number of the wafer W is decreased at time t3 and maintained at 1000 rpm, and for 3 seconds from time t3 to t4, for example 75 sccm, toward the wafer W. Discharge at a flow rate of

As described above, in the wafer W after the step of drying the surface of the wafer W, the particles on the surface are easily moved. Further, since the surface of the wafer W is dry, the peripheral edge of the liquid pool of the thinner 100 spread on the surface of the wafer W pushes away particles while being rounded in cross section.
Then increase the rotational speed of the wafer W at time t4, while maintaining the 3000rpm from the time t4 to time t5 after 3 seconds, the N ₂ gas nozzle 5 by moving the nozzle unit 6, as shown in FIG. 7 wafer It is moved to the position where the gas is discharged toward the center of W, and the N ₂ gas is discharged. As a result, the thinner 100 on the surface of the wafer W is shaken off and the surface of the wafer W is dried. Thereafter, the discharge of the N ₂ gas is stopped, and the nozzle unit 6 is moved to move the thinner nozzle 4 toward the center of the wafer W to a position where the thinner is discharged.

Thereafter, at time t5, the rotational speed of the wafer W is lowered and maintained at 1000 rpm, and as shown in FIG. 8, the cleaning liquid is directed to the wafer W. Here, the thinner 100 is flowed for 6 seconds from time t5 to t6, for example, at a flow rate of 75 sccm. Discharge. Thus, the thinner 100 spreads the surface of the dried wafer W, and particles remaining on the surface of the wafer W are pushed by the air-liquid interface and removed.
That is, in this example, water is removed from the surface of the wafer W to form a dried state, and then the periphery of the pool of the thinner 100, which is spread along the surface of the wafer W, is rounded in cross section. In this state, the action of pushing out the particle 101 is performed twice.

  Thereafter, the nozzle unit 6 is retracted out of the wafer W, and the wafer W is rotated at a rotational speed of 2000 rpm for 0.3 seconds, and then the wafer W is rotated at a rotational speed of 500 rpm for 0.2 seconds. Further, the coating solution nozzle 3 is moved toward the center of the wafer W to a position where the coating solution 102 is to be coated. Then, from time t7, the rotational speed of the wafer W is increased and maintained at a rotational speed of 3000 rpm, and the coating liquid 102 is supplied for 1.5 seconds as shown in FIG. 2 (d) and FIG. As a result, the coating liquid 102 supplied to the surface of the wafer W spreads over the entire surface of the wafer W wetted by the thinner by centrifugal force.

  In the above-described embodiment, before supplying the coating liquid 102 to the wafer W carried into the coating apparatus, the thinner 100 is first supplied to wet the surface of the wafer W, and then the surface of the wafer W is dried. As a result, moisture on the surface of the wafer W is removed, and the particles 101 easily flow. Subsequently, when the thinner 100 is supplied to the surface of the wafer W, the gas-liquid interface of the thinner 100 spreads on the surface of the wafer W, and the gas-liquid interface can push the particles with a large force. It can be removed reliably. Therefore, when the coating liquid 102 is applied to the wafer W thereafter, formation of comet spots on the SOC film due to the adhesion of the particles 101 can be suppressed.

  At this time, the entire surface of the wafer W is wetted with the thinner 100, and then the surface of the wafer W is dried, and the supply of the thinner 100 facilitates removal of particles as shown in a verification test described later. This mechanism is presumed as follows. When the surface of the wafer W is wet, the surface of the wafer W and the thinner 100 become familiar. Therefore, the contact angle of the pool of thinner flowing on the surface of the wafer W becomes small, and the air-liquid interface of the thinner 100 becomes smooth as shown in FIG. Therefore, when the thinner 100 spreads on the surface of the wafer W, the force pressing the particles 101 from the side becomes weak and flows above the particles, and the force weakens particularly in the region near the outer periphery of the wafer W and the particles easily remain. .

  On the other hand, by drying the surface of the wafer W, the water repellency of the surface of the wafer W is improved, and the contact angle of the liquid pool of the thinner flowing on the surface of the wafer W is increased. Therefore, as shown in FIG. 11, when the thinner 100 is supplied to the surface of the wafer W, the cross section of the pool of the thinner 100 is rounded, and the particles 101 can be pushed from the side by a surface and can be pushed with a large force. The strong force can be maintained even in the area near the outer periphery of the wafer W. Therefore, it is estimated that the particle removal efficiency is improved. As a result, as shown in a verification test described later, the particles 101 can be efficiently removed even when the flow rate of the cleaning solution is reduced or when the supply time of the cleaning solution is set short.

Further, the supply time of the thinner 100 supplied toward the wafer W from time t5 to t6 immediately before the supply of the coating liquid 102 to the wafer W is set to 6 seconds. Since the drying is accelerated by spraying N ₂ gas toward the wafer W to accelerate the evaporation, the temperature of the wafer W, particularly the temperature of the region on the outer peripheral side of the wafer W is easily lowered by the evaporation cooling. It may affect the drying time etc. Since the thinner 100 is supplied at normal temperature (25 ° C.), the wafer lowered by the gas spray by prolonging the supply time of the thinner 100 supplied toward the wafer W immediately before supplying the resist solution to the wafer W The temperature of W can be returned to normal temperature.

In the above embodiment, the process of supplying the thinner 100 to the rotated wafer W and the process of supplying the N ₂ gas to the surface of the wafer W to dry the surface of the wafer W are repeated twice. However, the process of supplying the thinner 100 to the rotated wafer W and the process of supplying the N ₂ gas to the surface of the wafer W to dry the surface of the wafer W may be performed once.

After the surface of the wafer W is dried as described in the above-described embodiment, by supplying the thinner 100 to the wafer W, the particle 101 can be pushed with a large force by the air-liquid interface. Therefore, by repeating the process of supplying the thinner to the rotated wafer W and the process of supplying the N ₂ gas to the surface of the wafer W to dry the surface of the wafer W, the number of times the particle 101 is pressed at the gas-liquid interface can be reduced. As it increases, particles can be removed more reliably. Further, the step of supplying the thinner 100 which is the processing liquid (cleaning liquid) to the rotated wafer W and the step of supplying the N ₂ gas to the surface of the wafer W to dry the surface of the wafer W are repeated three times or more. Good.

  In drying the surface of the wafer W, the wafer W may be rotated to shake off the thinner 100. However, as shown in Verification Test 3 described later, after supplying the thinner to the wafer W, the thinner may be removed. By stopping and rotating the wafer W and supplying nitrogen gas to the wafer W, the particle removal rate can be enhanced even with a short drying time. Therefore, the processing time of the wafer W can be shortened.

  Furthermore, when the wafer W is wetted for the first time, the supply time of the thinner, that is, the time to discharge the thinner as the processing liquid may be set shorter than the time to discharge the thinner as the cleaning liquid. For example, the time from time t1 to t2 for discharging the treatment liquid shown in FIG. 2 is set to 1 second, the time from time t3 to t4 for discharging the first cleaning liquid is 3 seconds, and the time for discharging the second cleaning liquid The time from t3 to t4 is set to 6 seconds respectively. It is sufficient that the processing liquid can supply a sufficient amount to wet the surface of the wafer W, and the inventors have found that there is no change in the removal performance even when the supply time of the processing liquid is shortened. . As a result, the processing time of the wafer W can be shortened. Further, even when the processing liquid and the cleaning liquid are supplied once, the discharge time of the processing liquid may be shorter than the supply time of the cleaning liquid.

  Further, the processing liquid to be supplied to the wafer W may be, for example, alcohol, as it is sufficient to remove the moisture on the surface of the wafer W. For example, TMAH (tetramethyl ammonium hydroxide), or an APM cleaning treatment solution (ammonia / hydrogen peroxide / water mixture solution) may be used. These chemical solutions wet the surface of the wafer W and can remove the particles adhering to the surface of the wafer W, so that the particles can be removed more efficiently. Alternatively, pure water may be supplied by supplying pure water to the surface of the wafer W and then drying it, as it has the effect of removing water. Further, after the wafer W is carried in, the wafer W is dried using a thinner as a processing solution to be supplied first, and then, for example, TMAH is supplied as a cleaning liquid to be supplied to the wafer W, and then the wafer W is dried A thinner may be supplied as a cleaning solution. Further, the cleaning liquid may be a solvent for performing pre-wet processing to make the wafer W wet and spread the coating liquid easily, and the processing liquid may be the same solvent for the pre-wet processing as the cleaning liquid.

  Further, when supplying the processing liquid and the cleaning liquid to the wafer W, the nozzle is moved in the circumferential direction of the wafer W while discharging the processing liquid and the cleaning liquid to the wafer W, and the discharge position of the processing liquid and the cleaning liquid is moved in the circumferential direction of the wafer W You may do so. The treatment liquid and the cleaning liquid may be the same chemical solution, for example, a solvent, or may be different chemical solutions, for example, different solvents.

Further, in the case where the drying and the supply of the cleaning liquid are repeated plural times, the rotation direction of the wafer W may be alternately switched between each time. When this method is applied to the embodiment described above, the rotation direction of the wafer during t3-t4 and the rotation direction of the wafer W during t1-t2 and between t5-t6 are opposite to each other.
In addition, when the rotational speed of the wafer W becomes high, the wafer W is easily cooled. Therefore, the rotation speed of the wafer W in the step of drying the wafer W is preferably 1000 to 3000 rpm. Further, from the viewpoint of sufficiently drying the wafer W and suppressing the influence on the throughput, the step of drying the wafer W (the time from the supply stop of the thinner to the start of the supply of the thinner following) is 3 seconds to 6 seconds. Is preferred.
Further, the time for supplying the cleaning liquid to the wafer W is preferably 3 seconds or more.

The wafer W to which the coating solution is applied may be a wafer W on which a step pattern is formed. For example, in the step of forming a step pattern such as an etching process, particles are easily generated, and particles are easily attached to the wafer W after the step pattern is formed. In addition, when the step pattern is formed on the wafer W, there is a problem that particles are easily caught in the step pattern and the particles are less likely to flow. As shown in the verification test described later, the effect can be obtained by applying the present invention to the wafer W on which the step pattern is formed.
The coating solution may be a coating solution for forming a resist film, an antireflective film, or the like.

[Verification test 1]
The present inventors have found out the present invention by examining the influence on the particle removal efficiency by variously setting the supply time of the thinner to the wafer, the rotation speed at the time of thin supply, parameters such as the flow rate of the thinner, and the cleaning method. . Hereinafter, various verification tests leading to the present invention and the results thereof will be described. The verification test also includes the method of the present invention.

[Obtain data of reference example]
Polystyrene latex particles (PSL particles) with a diameter of 25 μm are attached to the surface of the inspection wafer W, and the inspection wafer W is rotated at a rotational speed of 2000 rpm for 1 second in the coating apparatus shown in the embodiment. A thinner (OK 73) was supplied at a flow rate of 75 ml / min for 12 seconds toward the center of the inspection wafer W while rotating at a rotational speed. Thereafter, the wafer W on which the surface was dried by rotating the inspection wafer W at a rotation speed of 2000 rpm for 4.5 seconds, a rotation speed of 100 rpm for 1 second, and a rotation speed of 1500 rpm for 15 seconds was used as a reference example. -1]
An example processed in the same manner as the reference example except that the time for supplying the thinner was set to 18 seconds while rotating the inspection wafer W was taken as a verification test 1-1.
[Verification test 1-2]
An example processed in the same manner as the verification test 1-1 except that the rotational speed of the wafer W was set to 2000 rpm when supplying the thinner while rotating the inspection wafer W was designated as a verification test 1-2.
[Verification test 1-3]
An example processed in the same manner as the verification test 1-1 except that the rotation speed of the wafer W was set to 3000 rpm when supplying the thinner while rotating the inspection wafer W was designated as a verification test 1-3.
[Verification test 1-4]
An example processed in the same manner as the verification test 1-1 was a verification test 4 except that the flow rate of the thinner when supplying the thinner while rotating the inspection wafer W was set to 150 ml / min.

  For each of the reference example and the verification tests 1-1 to 1-4, the number of PSL particles (diameter 1 μm or more) attached to the inspection wafer W before being transferred to the coating apparatus (the number of adhesion before test) Removal rate ((Number before adhesion after test-Number after adhesion after test) / Number before adhesion after test x 100)% was calculated from the difference value of the number of adhesion (number after adhesion after test) of PSL particles (diameter 1 μm or more) on wafer W .

  FIG. 12 shows this result, and shows the removal rate of PSL particles in the reference example and the verification tests 1-1 to 1-4. In the reference example, the removal rate of PSL particles was 10.5%. The removal rates of PSL particles in tests 1-1 to 1-4 are 13.0%, 14.8%, 15.4%, and 15.6%, respectively, and the removal rate of PSL particles is higher than that of the reference example. It was getting high.

  From the removal rate of PSL particles in the reference example and verification test 1-1, it can be said that the removal rate of particles is increased by prolonging the supply time of the thinner. Further, from the results of the verification tests 1-1 to 1-3, it can be said that the particle removal rate is increased by increasing the number of rotations of the inspection wafer W when supplying the thinner while rotating the inspection wafer W. In addition, since the rate of removal of particles is higher in the verification test 1-4 than in the verification test 1-1, the particle removal rate is increased by supplying a thinner flow rate while rotating the inspection wafer W. It can be said that the rate goes up.

[Verification test 2]
In supplying the thinner while rotating the inspection wafer W, the effect of moving the nozzle for supplying the thinner was verified.
[Verification test 2-1]
When supplying the thinner while rotating the inspection wafer W, the thinner is supplied for 6 seconds toward the center of the wafer W, and then the nozzle for discharging the thinner is discharged toward the center of the wafer W, An example processed in the same manner as in the reference example was a verification test 2-1 except that the thinner was supplied while being moved to the position for discharging toward the peripheral portion of the wafer W for 6 seconds.

Similarly to the verification test 2-1, the difference value between the pre-test adhesion number of PSL particles and the post-test adhesion number of PSL particles in the inspection wafer W was determined, and the removal rate of PSL particles was calculated.
FIG. 13 shows the results and is a characteristic chart showing the removal rate of PSL particles in the reference example and the verification test 2-1. In Verification Test 2-1, the removal rate of PSL particles was 18.4%, which was higher than that of the reference example.
Therefore, when supplying the thinner while rotating the inspection wafer W, it can be said that the removal rate of particles is increased by moving the nozzle for supplying the thinner.

[Verification test 3]
In supplying the thinner while rotating the inspection wafer W, the effect of intermittently supplying the thinner was verified.
[Verification test 3-1]
In the reference example, in supplying the thinner while rotating the inspection wafer W, the supply of the thinner toward the central portion of the wafer W is performed for 6 seconds while rotating the inspection wafer W at a rotational speed of 1000 rpm for 6 seconds, and then After the wafer W for inspection is rotated at a rotational speed of 1000 rpm for 6 seconds while the thinner is stopped to remove the thinner on the surface of the wafer W for inspection, the wafer W for inspection is further rotated for 6 seconds at a rotational speed of 1000 rpm An example in which a thinner was supplied for 6 seconds toward the central portion of the wafer W was designated as a verification test 3-1.
[Verification test 3-2]
In order to supply the thinner while rotating the inspection wafer W, when removing the thinner on the surface of the inspection wafer W, the number of revolutions of the inspection wafer W is set to the number of revolutions of 2000 rpm and it is rotated for 6 seconds. An example in which the same processing as the verification test 3-1 was performed except for the above is called a verification test 3-2.
[Verification test 3-3]
In order to supply the thinner while rotating the inspection wafer W, when removing the thinner on the surface of the inspection wafer W, the number of rotations of the inspection wafer W is set to the number of rotations of 3000 rpm and it is rotated for 6 seconds. An example in which the same processing as the verification test 3-1 was performed except for the above is called a verification test 3-3.
[Verification test 3-4]
In order to supply the thinner while rotating the inspection wafer W, when removing the thinner on the surface of the inspection wafer W, the number of rotations of the inspection wafer W is set to the number of rotations of 3000 rpm and it is rotated for 2 seconds. An example in which the same processing as the verification test 3-1 was performed except for the above is called a verification test 3-4.
[Verification test 3-5]
After supplying the thinner while rotating the inspection wafer W, when removing the thinner on the surface of the inspection wafer W, the number of rotations of the inspection wafer W is set to the number of rotations of 3000 rpm and it is rotated for 4 seconds. An example in which the same processing as the verification test 3-1 was performed except for the above is referred to as a verification test 3-5.

Similarly, in the verification tests 3-1 to 3-5, the difference value between the pre-test adhesion number of PSL particles and the post-test adhesion number of PSL particles in the inspection wafer W was determined to calculate the removal rate of PSL particles.
FIG. 14 is a characteristic diagram showing the results and showing the removal rate of PSL particles in the reference example and the verification tests 3-1 to 3-3. FIG. 15 is a characteristic diagram showing the removal rate of PSL particles in the verification test 3-3 and the reference example together with the verification tests 3-4 and 3-5.

As shown in FIG. 14, in the verification tests 3-1 to 3-3, the removal rates of PSL particles were 10.7%, 12.9%, and 53.7%, respectively. The inspection wafer W after the test was not dried in the verification tests 3-1 and 3-2, but was sufficiently dried in the verification test 3-3.
According to this result, the surface of the wafer W can be dried by setting the number of rotations of the wafer for inspection W to the number of rotations of 3000 rpm when removing the thinner on the surface of the wafer W for inspection. It can be said that the particles on the surface of the wafer W can be efficiently removed when the thinner is supplied.

In addition, as shown in FIG. 15, in the verification tests 3-4 and 3-5, the removal rates of the PSL particles were 10.5% and 14.6%, respectively.
From the results of verification tests 3-3 to 3-5, when removing the thinner on the surface of the wafer for inspection W, the number of rotations of the wafer for inspection W is set to the number of rotations of 3000 rpm, and more effectively for 4 seconds or more. It can be said that the surface of the wafer W can be dried by rotating for 6 seconds or more, and particles on the surface of the wafer W can be efficiently removed when a thinner is subsequently supplied.

[Additional examination of verification examination 3]
In addition, after supplying the thinner while rotating the inspection wafer W, the supply of the thinner is stopped, the N ₂ gas is supplied, and then the effect of supplying the thinner is verified.
[Verification test 3-3a]
In the verification test 3-3, when removing the thinner on the surface of the wafer for inspection W, the number of rotations of the wafer for inspection W is set to the number of rotations of 3000 rpm and N ₂ gas is supplied toward the wafer for inspection W As a verification test 3-3a.
[Verification test 3-4a]
In Verification Test 3-4, when removing the thinner on the surface of inspection wafer W, the number of rotations of inspection wafer W is set to the number of rotations of 3000 rpm, and it is rotated for 2 seconds and directed to inspection wafer W N ₂ The example which supplied gas was made into verification test 3-4a.
[Verification test 3-5a]
In the verification test 3-5, when removing the thinner on the surface of the inspection wafer W, the number of rotations of the inspection wafer W is set to the number of rotations of 3000 rpm, and it is rotated for 4 seconds and directed to the inspection wafer W N ₂ The example which supplied gas was made into verification test 3-5a.
[Verification test 3-4b]
After N ₂ gas is supplied to the surface of inspection wafer W, the time for supplying thinner for 3 seconds toward the center of wafer W while rotating inspection wafer W at a rotational speed of 1000 rpm is set except An example processed in the same manner as the verification test 3-4a is referred to as a verification test 3-4b.
Similarly, for the verification tests 3-3a to 3-5a and the verification test 3-4b, the difference value between the pre-test adhesion number of PSL particles and the post-test adhesion number of PSL particles in the inspection wafer W is determined, and the removal rate of PSL particles Was calculated.

FIG. 16 is a characteristic diagram showing the removal rate of PSL particles in the verification tests 3-3a to 3-5a together with the removal rate of PSL particles in the verification tests 3-3 to 3-5. FIG. 17 is a characteristic diagram showing the removal rate of PSL particles in verification test 3-4b, as well as the removal rate of PSL particles in verification test 3-4a and the reference example.
As shown in FIG. 16, the removal rates of PSL particles in verification tests 3-3a to 3-5a are 54.2%, 50.2%, and 53.8%, respectively, and all removal rates exceed 50%. The Further, as shown in FIG. 17, in the verification test 3-4b, the removal rate of PSL particles showed a high value of 59.1%. In the additional test of verification test 3 and verification test 4 described later, data of the reference example was acquired again. As a result, the removal rate of PSL particles of the reference example was 12.2%, which was almost the same as the value obtained in Verification Test 1, and the removal rate did not change.

14. In verification tests 3-4 and 3-5 in which intervals of time for discharging the thinner toward the inspection wafer W are set to 2 seconds and 4 seconds, respectively, the removal rate of PSL particles is 12.2% and 14.%, respectively. Since it is 6%, when removing the thinner on the surface of the wafer for inspection W, the number of rotations of the wafer for inspection W is set to the number of rotations of 3000 rpm and N ₂ gas is supplied toward the wafer for inspection W Therefore, it can be said that particles can be efficiently removed even in a short time. From The possible removal rate of PSL particles in any of the verification test 3-4a and validation testing 3-4b as shown in FIG. 17 is a high value, to be dried by blowing N ₂ gas when drying the wafer W Then, it can be said that particles can be efficiently removed even when the time for supplying the thinner is set to be short.

[Verification test 4]
In addition, in order to intermittently supply the thinner to the inspection wafer W, the drying time when stopping the thinner and drying the wafer W, and the effect of repeating the supply of the thinner of the wafer W and the drying of the wafer W a plurality of times Verified.
[Verification test 4-1]
In verification test 3-4b, the rotational speed of inspection wafer W is set to a rotational speed of 3000 rpm while supplying N ₂ gas toward inspection wafer W when removing the thinner on the surface of inspection wafer W. An example of rotating for 3 seconds was taken as verification test 4-1.
[Verification test 4-2]
Further, following the processing of verification test 4-1, while the wafer W for inspection is rotated for 3 seconds at a rotational speed of 1000 rpm in a state where the thinner is stopped, N ₂ gas is supplied to remove the thinner on the surface of the wafer W for inspection After that, an example in which a thinner was supplied toward the center of the wafer W for 3 seconds while rotating the inspection wafer W at a rotational speed of 1000 rpm was referred to as a verification test 4-2.
Similarly, in the verification tests 4-1 to 4-2, the difference value between the pre-test adhesion number of PSL particles and the post-test adhesion number of PSL particles in the inspection wafer W was determined to calculate the removal rate of PSL particles.

  FIG. 18 is a characteristic diagram showing this result and the removal rate of PSL particles in verification test 3-4b, as well as the removal rate of PSL particles in verification test 4-1 and verification test 4-2. In Verification Test 3-4b, the removal rate of PSL particles showed a high value of 59.1%, but in Verification Test 4-1, the removal rate of PSL particles was 67.2%, and Verification Test 4 At -2, the removal rate of PSL particles was 72.9%.

According to this result, the particle removal rate is increased by lengthening the time for supplying the N ₂ gas while rotating the inspection wafer W in a state in which the thinner is stopped, and the inspection wafer W in a state in which the thinner is stopped. It can be said that the particle removal rate is increased by repeating the process of supplying the N ₂ gas while rotating and the process of supplying the thinner to the surface of the inspection wafer W while rotating the inspection wafer W.

  As described above, when the supply time of the thinner is increased, the rotational speed of the wafer W is increased, and when the flow rate of the thinner is increased, the removal rate of particles is increased. It can be said that particles can be removed efficiently by doing this. Further, the drying time can be shortened by blowing a gas onto the wafer W when drying the wafer W, and the flow rate of thinner can also be reduced. Further, by repeating the process of supplying the thinner to the wafer W and the process of drying the wafer W a plurality of times, particles can be removed more efficiently.

  Further, an SOC film was formed subsequently to the inspection wafer W subjected to each process of the reference example, verification test 3-4b and verification test 4, and the number of comet spots formed on the SOC film was counted. The number of comet spots counted on the inspection wafer W of each of the reference example, the verification test 3-4 b and the verification test 4 was 214, 118 and 7 respectively. In the verification test 3-4b, the number of comet spots is significantly reduced as compared with the reference example, and it is understood that the verification test 4 further reduces the number.

  In addition, processing of each of the reference example, verification test 3-4b and verification test 4 was performed on the wafer on which the step pattern was formed instead of the inspection wafer W, and the SOC film was subsequently formed to form the SOC film. The number of comet spots was counted. The number of comet spots counted on the wafer W of the reference example, verification test 3-4b and verification test 4 was 84, 20 and 4 respectively. From this result, it can be said that even when the present invention is applied to a wafer W on which a step pattern is formed, particles can be similarly removed, and formation of comet spots on a coating film can be suppressed.

Reference Signs List 2 cup body 3 coating solution nozzle 4 thinner nozzle 5 N ₂ gas nozzle 6 nozzle unit 100 thinner 101 particle 102 coating solution W wafer

Claims (14)

Holding the substrate horizontally;
Next, the entire surface of the substrate is wetted with a processing solution,
And then rotating the substrate about a vertical axis to dry the surface of the substrate;
Supplying a cleaning solution to the surface of the substrate while rotating the substrate around a vertical axis;
And thereafter supplying a coating solution to the surface of the substrate to form a coating film.   The coating method according to claim 1, wherein the cleaning solution is an organic solvent.   The coating method according to claim 1, wherein the treatment liquid is either tetramethyl ammonium hydroxide or an ammonia / hydrogen peroxide / water mixed solution.   The coating method according to claim 1, wherein the processing liquid and the cleaning liquid are the same organic solvent. After the step of supplying the cleaning liquid to the surface of the substrate,
Rotating the substrate about a vertical axis to dry the surface of the substrate;
2. A coating method according to claim 1, further comprising the step of: supplying a cleaning liquid to the surface of the substrate while rotating the substrate around a vertical axis.   The coating method according to claim 1, wherein in the step of rotating the substrate about the vertical axis to dry the surface of the substrate, the substrate is rotated about the vertical axis and a gas is discharged toward the substrate.   2. The method according to claim 1, wherein the rotational direction of the substrate in the step of supplying the processing liquid to the substrate and the rotational direction of the substrate in the step of supplying the first cleaning liquid to the substrate are opposite to each other. Method of application   The coating method according to claim 1, wherein the step of supplying the cleaning liquid to the substrate is supplying the cleaning liquid for 3 seconds or more.   The coating method according to claim 1, wherein a supply time of the processing liquid in the step of wetting the entire surface of the substrate with the processing liquid is shorter than a supply time of the cleaning liquid in the step of supplying the cleaning liquid to the surface of the substrate.   The step of supplying the processing liquid to the substrate and the step of supplying the cleaning liquid to the substrate include the step of supplying the processing liquid and the cleaning liquid while moving the supply position of the cleaning liquid from the center of the substrate toward the periphery of the substrate. The application method according to claim 1.   A storage medium storing a computer program for use in a coating apparatus for supplying a coating solution to a substrate which is held horizontally and rotated about a vertical axis to be coated, and executes the coating method according to claim 1 A storage medium characterized in that the steps are combined. A substrate holder for holding the substrate horizontally;
A rotation mechanism for rotating the substrate holding unit around a vertical axis;
A coating solution nozzle for supplying a coating solution to the substrate held by the substrate holding unit;
A treatment liquid nozzle for supplying a treatment liquid to the substrate held by the substrate holding unit;
A cleaning solution nozzle for supplying a cleaning solution to the substrate held by the substrate holding unit;
Holding the substrate horizontally, then wetting the entire surface of the substrate with a treatment solution, and then rotating the substrate about a vertical axis to dry the surface of the substrate, and then rotating the substrate about the vertical axis Applying a cleaning solution to the surface of the substrate while rotating it, and then supplying a coating solution to the surface of the substrate to form a coating film. apparatus.   13. The coating apparatus according to claim 12, wherein the processing liquid and the cleaning liquid are the same solvent, and the processing liquid nozzle and the cleaning liquid nozzle are shared. A gas supply nozzle for supplying gas toward the substrate;
The coating method according to claim 12, wherein, in the step of drying the surface of the substrate, the control unit outputs a control signal to discharge gas toward the substrate while rotating the substrate about a vertical axis. apparatus.

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