JP6690717B2 - Coating method, coating device and storage medium - Google Patents

Description

  The present invention relates to a technique of supplying a coating liquid on the surface of a substrate to form a coating film.

  As one of the semiconductor manufacturing processes, a coating liquid is supplied to a semiconductor wafer (hereinafter referred to as “wafer”), and an SOC (Spin On) containing carbon as a coating film, for example, a resist film, an antireflection film, or an etching mask is a main component. Cap) There is a process of forming a film. Spin coating is widely used in this process.

  For example, an etching mask such as an SOC film is formed so as to cover the surface of the wafer after forming the step pattern on the wafer. For example, particles generated in a previous process such as an etching process for forming the step pattern on the wafer It may adhere to the surface of the wafer. After that, when the coating liquid was supplied to the wafer and spin coating was performed, the spread of the coating liquid was hindered by the particles, and a comet-shaped spot (comet spot) with the particles as the core was sometimes formed in the coating film. Since semiconductor devices tend to be miniaturized more and more, such defects in the coating film cause a decrease 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 coating the coating liquid to clean the surface and remove particles. From the viewpoint of maintaining throughput, there has been a demand for efficiently removing particles in a shorter time. Further, from the viewpoint of avoiding an increase in the size of the apparatus, cleaning of particles in a module for coating has been required.

JP, 2006-208456, A

  The present invention has been made under such circumstances, and an object of the invention is to remove particles in a short time when applying a coating liquid to a substrate to form a coating film and to prevent the occurrence of defects in the coating film. It is to provide technology that can be suppressed.

The coating method of the present invention comprises a step of horizontally holding the substrate,
Next, a step of wetting the entire surface of the substrate with the processing liquid,
Then, rotating the substrate around a vertical axis , shaking off the treatment liquid on the surface of the substrate, and drying the surface of the substrate,
And then supplying a cleaning liquid, which is an organic solvent, to the surface of the substrate while rotating the substrate whose surface is dried around a vertical axis,
It is seen containing a step of forming a coating film by supplying a coating solution to the surface of Thereafter the substrate, and
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;
Thereafter, the step of supplying the cleaning liquid to the surface of the substrate while rotating the substrate having the dried surface on the vertical axis is performed .

  A storage medium according to the present invention is a storage medium that stores a computer program used in a coating apparatus that supplies a coating liquid to a substrate that is held horizontally and rotated around a vertical axis and that applies the coating method. It is characterized by a group of steps that are executed.

The coating apparatus of the present invention, a substrate holding unit for horizontally holding the substrate,
A rotation mechanism for rotating the substrate holding unit around a vertical axis,
A coating liquid nozzle for supplying a coating liquid to the substrate held by the substrate holding part,
A processing liquid nozzle for supplying a processing liquid to the substrate held by the substrate holding part;
A cleaning liquid nozzle that supplies a cleaning liquid that is an organic solvent to the substrate held by the substrate holding unit,
Holding the substrate horizontally, then wetting the entire surface of the substrate with the processing liquid, and then rotating the substrate around a vertical axis to shake off the processing liquid on the surface of the substrate and dry the surface of the substrate. a step of, steps thereafter the step of supplying the cleaning solution to the dried surface of the substrate while rotating the substrate about a vertical axis of the surface, then rotating the substrate around a vertical axis, to dry the surface of the substrate Then , a step of supplying the cleaning liquid to the surface of the substrate while rotating the substrate whose surface has been dried around a vertical axis, and then supplying a coating liquid to the surface of the substrate to form a coating film. And a control unit for executing.

In 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 easier for the particles to separate from the surface of the substrate. Further, by drying the surface of the substrate, when the cleaning liquid is continuously supplied to the surface of the substrate, the particles can be pushed by the gas-liquid interface with a large force, and the particles can be removed more reliably in a short time. Therefore, it is possible to suppress the formation of spots on the coating film due to the adhesion of particles when the substrate is subsequently coated with the coating liquid.
Further, since the coating apparatus of the present invention has the function of cleaning the substrate, it is not necessary to provide a separate cleaning apparatus.

It is sectional drawing of the SOC film coating device which concerns on embodiment of this invention. It is explanatory drawing which matched the time chart of the rotation speed of a wafer, and a process. 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. It is a characteristic view which shows the removal rate of the PSL particle in the verification test 1. It is a characteristic view which shows the removal rate of the PSL particle in the verification test 2. It is a characteristic view which shows the removal rate of the PSL particle in the verification test 3. It is a characteristic view which shows the removal rate of the PSL particle in the verification test 3. It is a characteristic view which shows the removal rate of the PSL particle in the verification test 3. It is a characteristic view which shows the removal rate of the PSL particle in the verification test 3. It is a characteristic view which shows the removal rate of the PSL particle in the verification test 4.

  As an example of the 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 a central portion of the back surface of the wafer W and holds it horizontally. The spin chuck 11 is connected to the rotating mechanism 13 from below via the shaft portion 12, and can be rotated about the vertical axis by the rotating mechanism 13.

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

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

Further, a vertical tubular portion 22 is provided so as to surround the outside of the mountain-shaped guide portion 21, and an upper guide portion 24 that obliquely extends inward from the upper edge of the tubular portion 22 toward the upper inside. The upper guide portion 24 is provided with a plurality of openings 25 in the circumferential direction. Further, on the lower side of the tubular portion 22, a ring-shaped liquid receiving portion 26 having a concave cross section is formed below the mountain-shaped guide portion 21 and the vertical wall 23. In the liquid receiving portion 26, a drainage passage 27 is connected to the outer peripheral side, and an exhaust pipe 28 is provided inward from the drainage passage 27 so as to protrude from below.
Further, a tubular 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 upward inward from the upper edge of the tubular 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 is introduced into the drainage passage 27.

The coating apparatus includes a coating liquid nozzle 3 that supplies a coating liquid in which an organic material, which is a precursor of the SOC film, is dissolved in a solvent to the wafer W. The coating liquid nozzle 3 is connected to a coating liquid supply mechanism 32 via a coating liquid supply pipe 31. As the coating liquid, a liquid obtained by dissolving an organic material containing a carbon compound, for example, a polymer raw material having a skeleton of a polyethylene structure ((—CH ₂ —) _n ) 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, it 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 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. 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 liquid nozzle 3 and the nozzle unit 6 are configured to move between the upper center portion of the wafer W and the standby position outside the cup body 2 by a moving mechanism (not shown).

The coating device is provided with a control unit 10 including, for example, a computer. The control unit 10 has a program storage unit, and in the program storage unit, the transfer of the wafer W between the external transfer arm and the spin chuck 11, rotation of the spin chuck 11, coating liquid, thinner. And a program is stored, which is instructed to execute the supply sequence of N ₂ gas. This program is stored in a storage medium such as 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.

Next, 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-mentioned wafer W is transferred to the spin chuck 11 by the cooperation of an external transfer arm (not shown) and the elevating pins 15.
First, in order to align the orientation of the wafer W, as shown in FIG. 2A, the wafer W is rotated at a rotation speed of 2000 rpm for 1 second from the time t0. 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 where the thinner which is the processing liquid is discharged.

  Next, as shown in FIG. 2A, at time t1, the rotation speed of the wafer W is lowered to maintain 1000 rpm, and the thinner 100 is moved toward the wafer W at time t1 as shown in FIGS. 2B and 4. Discharge at a flow rate of, for example, 75 sccm for 3 seconds from t2 to t2. As a result, the thinner 100 spreads on the surface of the wafer W by centrifugal force, and the entire surface of the wafer W becomes wet.

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

Water is adsorbed on the surface of the wafer W before the thinner 100 is supplied. Although the particles adhere to the surface of the wafer W, microscopically, it is considered that the particles are adsorbed by the water on the surface of the wafer W. Therefore, in this example, when the thinner 100 is supplied to the center of the rotating wafer W and the thinner is expanded, the water absorbed by the surface of the wafer W is washed away by the thinner 100. Further, the number of revolutions of the wafer W is increased to shake off the thinner 100 and the surface of the wafer W is dried by blowing N ₂ gas, so that the particles attached to the surface of the wafer W are easily moved. The thinner 100 supplied at the time t1 is a processing liquid that is a liquid for removing the water on the surface of the wafer W, but the particles adhering to the surface of the wafer W due to the expansion due to the rotation of the wafer W. It can be said to be a cleaning liquid because it plays a role of rinsing a part of

After that, the discharge of the N ₂ gas is stopped, the nozzle unit 6 is moved, and the thinner nozzle 4 is moved toward the center of the wafer W to the position where the thinner 100 as the cleaning liquid is discharged. Then, as shown in FIGS. 2B and 6, at time t3, the rotation speed of the wafer W is lowered to maintain 1000 rpm, and the thinner 100 is directed toward the wafer W for 3 seconds from time t3 to t4, for example, 75 sccm. Discharge at the flow rate of.

After the step of drying the surface of the wafer W as described above, the particles on the surface of the wafer W 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 the particles in a rounded state when viewed in cross section.
Subsequently, at time t4, the rotation speed of the wafer W is increased and maintained at 3000 rpm from time t4 to time t5 three seconds later, and the nozzle unit 6 is moved to move the N ₂ gas nozzle 5 to the wafer as shown in FIG. The N ₂ gas is discharged by moving it to the position where the gas is discharged toward the center of W. 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. After that, the discharge of the N ₂ gas is stopped, the nozzle unit 6 is moved, and the thinner nozzle 4 is moved toward the center of the wafer W to the position where the thinner is discharged.

After that, at time t5, the rotation speed of the wafer W is lowered and maintained at 1000 rpm, and as shown in FIG. Discharge. As a result, the thinner 100 spreads over the surface of the dried wafer W, and the particles remaining on the surface of the wafer W are pushed and removed by the gas-liquid interface.
That is, in this example, water is removed from the surface of the wafer W and a dry state is formed, and then the periphery of the liquid pool of the thinner 100, which is spread along the surface of the wafer W, is rounded in cross section. That is, the action of flushing the particles 101 is performed twice in the state of being present.

  Thereafter, the nozzle unit 6 is retracted to the outside of the wafer W, the wafer W is rotated at a rotation speed of 2000 rpm for 0.3 seconds, and then the wafer W is rotated at a rotation speed of 500 rpm for 0.2 seconds. Further, the coating liquid nozzle 3 is moved toward the center of the wafer W to a position where the coating liquid 102 is coated. Then, from the time t7, the rotation speed of the wafer W is increased and maintained at 3000 rpm, and the coating liquid 102 is supplied for 1.5 seconds as shown in FIG. 2D 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 wet by the thinner due to the 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, the water 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 over the surface of the wafer W, and this gas-liquid interface can push the particles with a large force, so that the particles can be more quickly It can be reliably removed. Therefore, when the coating liquid 102 is applied to the wafer W thereafter, it is possible to suppress the formation of comet spots on the SOC film due to the adhesion of the particles 101.

  At this time, the entire surface of the wafer W is wet with the thinner 100, the surface of the wafer W is dried, and then the thinner 100 is supplied, whereby particles are easily removed 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 compatible with each other. Therefore, the contact angle of the pool of thinner flowing on the surface of the wafer W becomes small, and the gas-liquid interface of the thinner 100 becomes gentle as shown in FIG. Therefore, when the thinner 100 spreads on the surface of the wafer W, the force pushing the particles 101 from the side becomes weak and the particles flow above the particles W, and the force becomes weak particularly in the region near the outer periphery of the wafer W and the particles tend to 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 pool of 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 liquid pool of the thinner 100 is rounded, and the particles 101 can be pushed laterally and with a large force. , A strong force can be maintained even in a region near the outer periphery of the wafer W. Therefore, it is estimated that the particle removal efficiency is improved. As a result, the particles 101 can be efficiently removed even when the flow rate of the cleaning liquid is reduced or the supply time of the cleaning liquid is set to be short, as shown in a verification test described later.

Further, the supply time of the thinner 100 supplied to the wafer W from time t5 to time t6 immediately before supplying the coating liquid 102 to the wafer W is set to 6 seconds. Since N ₂ gas is blown toward the wafer W to accelerate vaporization to accelerate the drying, the temperature of the wafer W, particularly the temperature of the outer peripheral side region of the wafer W, is easily lowered by the evaporative cooling. It may affect the drying time. Since the thinner 100 is supplied at room temperature (25 ° C.), the supply time of the thinner 100 supplied to the wafer W immediately before supplying the resist solution to the wafer W is lengthened, so that the wafer which has been deteriorated by the gas spray is reduced. The temperature of W can be returned to normal temperature.

Further, in the above-described embodiment, the step of supplying the thinner 100 to the rotated wafer W and the step of supplying N ₂ gas to the surface of the wafer W to dry the surface of the wafer W are repeated twice. However, the step of supplying the thinner 100 to the rotated wafer W and the step of supplying 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 shown in the above-described embodiment, by supplying the thinner 100 to the wafer W, the particles 101 can be pushed with a large force by the gas-liquid interface. Therefore, by repeating the step of supplying thinner to the rotated wafer W and the step of supplying N ₂ gas to the surface of the wafer W to dry the surface of the wafer W, the number of times the particles 101 are pushed at the gas-liquid interface is reduced. Since the number is increased, the particles can be removed more reliably. Even if the process of supplying the thinner 100 as the processing liquid (cleaning liquid) to the rotated wafer W and the process of supplying N ₂ gas to the surface of the wafer W to dry the surface of the wafer W are repeated three or more times. Good.

  When the surface of the wafer W is dried, the wafer W may be rotated and the thinner 100 may be shaken off to dry the surface. However, as shown in Verification Test 3 described below, after the thinner is supplied to the wafer W, the thinner is applied. By stopping and rotating the wafer W and supplying the nitrogen gas toward the wafer W, the removal rate of particles can be increased even in a short drying time. Therefore, the processing time of the wafer W can be shortened.

  Furthermore, when the wafer W is first wetted, the thinner supply time, that is, the time for discharging the thinner serving as the processing liquid may be set shorter than the time for discharging the thinner serving as the cleaning liquid. For example, the time from the time t1 to t2 for discharging the processing liquid shown in FIG. 2 is set to 1 second, the time from the time t3 to t4 for discharging the first cleaning liquid is 3 seconds, and the time for discharging the second cleaning liquid is set. The time from t3 to t4 is set to 6 seconds, respectively. It suffices that the treatment liquid can be supplied in an amount sufficient to wet the surface of the wafer W, and the inventors have found that the removal performance does not change even when the supply time of the treatment liquid is shortened. . As a result, the processing time of the wafer W can be shortened. Further, even when the treatment liquid and the cleaning liquid are supplied once, the discharge time of the treatment liquid may be shorter than the supply time of the cleaning liquid.

  The processing liquid supplied to the wafer W may be, for example, alcohol or the like, as long as the water on the surface of the wafer W is removed. Further, for example, TMAH (tetramethylammonium hydroxide) or a treatment liquid for APM cleaning (ammonia / hydrogen peroxide / water mixed liquid) or the like may be used. Since these chemicals can wet the surface of the wafer W and remove particles adhering to the surface of the wafer W, the particles can be removed more efficiently. Also, pure water may be used because it has the effect of removing water by supplying pure water to the surface of the wafer W and then drying it. After further loading the wafer W, a thinner is used as a processing liquid to be supplied first, the wafer W is dried, 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 the cleaning liquid. In addition, the cleaning liquid may be a solvent for performing a pre-wet process in which the wafer W is in a wet state to facilitate spreading of the coating liquid, and the processing liquid may be the same pre-wetting solvent 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 it. The treatment liquid and the cleaning liquid may be the same chemical liquid, for example, a solvent, or different chemical liquids, for example, different solvents.

When the supply of the drying-cleaning liquid is repeated a plurality of times, the rotation direction of the wafer W may be alternately switched between the respective times. When this method is applied to the above-described embodiment, the rotation direction of the wafer between t3 and t4 and the rotation direction of the wafer W between t1 and t2 and between t5 and t6 are opposite to each other.
Further, as the rotation speed of the wafer W increases, the wafer W is likely to be cooled. Therefore, the number of rotations 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 process of drying the wafer W (the time from the stop of the thinner supply to the start of the subsequent thinner supply) 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 liquid is applied may be a wafer W having a step pattern. For example, particles are likely to be generated in a step of forming a step pattern such as an etching process, and particles are easily attached to the wafer W after the step pattern is formed. Further, when the step pattern is formed on the wafer W, there is a problem that particles are easily caught by the step pattern and the particles are hard to flow. The effect can be obtained by applying the present invention to a wafer W having a stepped pattern as shown in a verification test described later.
The coating liquid may be a coating liquid for forming a resist film, an antireflection film, or the like.

[Verification test 1]
The present inventor found the present invention by investigating the influence on the particle removal efficiency by setting various parameters such as the time for supplying the thinner to the wafer, the rotational speed at the time of supplying the thinner, the flow rate of the thinner, and the cleaning method. . Various verification tests leading to the present invention and the results thereof will be described below. The verification test also includes the method of the present invention.

[Getting reference example data]
Polystyrene latex particles (PSL particles) having a diameter of 25 μm are attached to the surface of the inspection wafer W, the inspection wafer W is rotated for 1 second at a rotation speed of 2000 rpm by the coating apparatus shown in the embodiment, and then at 1000 rpm. The thinner (OK73) was supplied toward the center of the inspection wafer W at a flow rate of 75 ml / min for 12 seconds while rotating at the rotation speed. Thereafter, the wafer W for inspection was rotated at 2000 rpm for 4.5 seconds, at 100 rpm for 1 second, and at 1500 rpm for 15 seconds to dry the surface of the wafer W as a reference example. [Verification test 1 -1]
A verification test 1-1 was carried out in the same manner as the reference example except that the time during which the thinner was supplied while rotating the inspection wafer W was set to 18 seconds.
[Verification test 1-2]
A verification test 1-2 was carried out in the same manner as the verification test 1-1 except that the rotation speed of the wafer W when supplying the thinner while rotating the inspection wafer W was set to 2000 rpm.
[Verification test 1-3]
A verification test 1-3 was performed in the same manner as the verification test 1-1 except that the rotation speed of the wafer W when supplying the thinner while rotating the inspection wafer W was set to 3000 rpm.
[Verification test 1-4]
An example of verification test 4 was performed in the same manner as verification test 1-1 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 adhered PSL particles (diameter of 1 μm or more) (the number of adhered before the test) and the inspection after each process in the inspection wafer W before being transferred to the coating apparatus. The removal rate ((pre-test adhesion number-post-test adhesion number) / pre-test adhesion number × 100)% was calculated from the difference value of the adhesion number (post-test adhesion number) of PSL particles (diameter 1 μm or more) on the wafer W for use. .

  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 were 13.0%, 14.8%, 15.4%, and 15.6%, respectively, and the removal rates of PSL particles were higher than those of the reference example. It was getting higher.

  It can be said that the particle removal rate is increased by increasing the thinner supply time from the PSL particle removal rate in the reference example and the verification test 1-1. From the results of the verification tests 1-1 to 1-3, it can be said that the removal rate of particles is increased by increasing the number of rotations of the inspection wafer W when the thinner is supplied while rotating the inspection wafer W. Further, since the removal rate of particles in the verification test 1-4 is higher than that in the verification test 1-1, removal of particles is increased by increasing the flow rate of thinner when supplying thinner 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 from the position where the nozzle is discharged toward the center of the wafer W. A verification test 2-1 was performed in the same manner as in the reference example, except that the thinner was supplied while moving to a position where the wafer W was discharged toward the peripheral edge for 6 seconds.

Similarly for the verification test 2-1, the difference value between the number of pre-test adherence of PSL particles and the number of post-test adherence of PSL particles on the inspection wafer W was obtained, and the removal rate of PSL particles was calculated.
FIG. 13 is a characteristic diagram showing this result and showing the removal rate of PSL particles in the reference example and the verification test 2-1. In the verification test 2-1, the PSL particle removal rate was 18.4%, which was higher than that in the reference example.
Therefore, when supplying the thinner while rotating the inspection wafer W, it can be said that the particle removal rate is increased by moving the nozzle for supplying the thinner.

[Verification test 3]
When 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, when the thinner is supplied while rotating the inspection wafer W, the thinner is supplied toward the center of the wafer W for 6 seconds while rotating the inspection wafer W at the rotation speed of 1000 rpm for 6 seconds. With the thinner stopped, the inspection wafer W is rotated at a rotation speed of 1000 rpm for 6 seconds to remove the thinner on the surface of the inspection wafer W, and then the inspection wafer W is further rotated at 1000 rpm for 6 seconds. The verification test 3-1 is an example in which the thinner is supplied toward the center of the wafer W for 6 seconds.
[Verification test 3-2]
When supplying the thinner while rotating the inspection wafer W, when removing the thinner on the surface of the inspection wafer W, the rotation speed of the inspection wafer W was set to 2000 rpm and was rotated for 6 seconds. An example in which the same processing as that of the verification test 3-1 was performed except for was referred to as verification test 3-2.
[Verification test 3-3]
When supplying the thinner while rotating the inspection wafer W, when the thinner on the surface of the inspection wafer W is removed, the rotation speed of the inspection wafer W is set to 3000 rpm and is rotated for 6 seconds. An example in which the same processing as that of the verification test 3-1 was performed except for was referred to as verification test 3-3.
[Verification test 3-4]
When supplying the thinner while rotating the inspection wafer W, when removing the thinner on the surface of the inspection wafer W, the rotation speed of the inspection wafer W was set to 3000 rpm and the rotation was performed for 2 seconds. An example in which the same processing as that of the verification test 3-1 was performed except for was referred to as 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 rotation speed of the inspection wafer W was set to 3000 rpm and rotated for 4 seconds. An example in which the same processing as that of the verification test 3-1 was performed except for was designated as a verification test 3-5.

In the verification tests 3-1 to 3-5, similarly, the difference value between the number of pre-test adherence of PSL particles and the number of post-test adherence of PSL particles on the inspection wafer W was obtained, and the PSL particle removal rate was calculated.
FIG. 14 shows this result, and is a characteristic diagram showing the removal rate of PSL particles in the reference example and verification tests 3-1 to 3-3. FIG. 15 is a characteristic diagram showing PSL particle removal rates in the verification tests 3-3 and 3-5 as well as the verification tests 3-3 and the reference example.

As shown in FIG. 14, in verification tests 3-1 to 3-3, PSL particle removal rates 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 rotation speed of the inspection wafer W to 3000 rpm when removing the thinner on the surface of the inspection wafer W. It can be said that the particles on the surface of the wafer W can be efficiently removed when the thinner is supplied.

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

[Additional test of verification test 3]
Further, after the thinner was supplied while rotating the inspection wafer W, the supply of the thinner was stopped, the N ₂ gas was supplied, and then the effect of supplying the thinner was verified.
[Verification test 3-3a]
In the verification test 3-3, an example in which the rotation speed of the inspection wafer W is set to 3000 rpm and the N ₂ gas is supplied toward the inspection wafer W when removing the thinner on the surface of the inspection wafer W Was referred to as a verification test 3-3a.
[Verification test 3-4a]
In the verification test 3-4, when the thinner on the surface of the inspection wafer W is removed, the rotation speed of the inspection wafer W is set to 3000 rpm, the rotation speed is set to 2 seconds, and the inspection wafer W is rotated toward the N ₂ An example in which gas was supplied was used as verification test 3-4a.
[Verification test 3-5a]
In the verification test 3-5, when the thinner on the surface of the inspection wafer W is removed, the rotation speed of the inspection wafer W is set to 3000 rpm, the rotation speed is set to 4 seconds, and the N _{2 is} rotated toward the inspection wafer W. An example in which gas was supplied was designated as Verification Test 3-5a.
[Verification test 3-4b]
After supplying the N ₂ gas to the surface of the inspection wafer W, except that the time for supplying the thinner toward the central portion of the wafer W is set to 3 seconds while rotating the inspection wafer W at a rotation speed of 1000 rpm. Then, an example of processing similar to that of the verification test 3-4a is referred to as a verification test 3-4b.
Regarding the verification tests 3-3a to 3-5a and the verification test 3-4b, similarly, a difference value between the number of pre-test adherence of PSL particles and the number of post-test adherence of PSL particles on the inspection wafer W is obtained, and the removal rate of PSL particles is obtained. Was calculated.

FIG. 16 is a characteristic diagram showing the removal rate of PSL particles in the verification tests 3-3a to 3-5a and the removal rate of PSL particles in the verification tests 3-3 to 3-5. FIG. 17 is a characteristic diagram showing the PSL particle removal rate in the verification test 3-4b and the PSL particle removal rate in the verification test 3-4a and the reference example.
As shown in FIG. 16, the removal rates of PSL particles in the verification tests 3-3a to 3-5a were 54.2%, 50.2%, and 53.8%, respectively, all of which were over 50%. It was In addition, as shown in FIG. 17, in the verification test 3-4b, the removal rate of PSL particles was a high value of 59.1%. In addition, in the additional test of the verification test 3 and the verification test 4 described later, the data of the reference example was acquired again. As a result, the removal rate of PSL particles in 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.

In verification tests 3-4 and 3-5 in which the intervals of the time when the thinner is ejected toward the inspection wafer W are set to 2 seconds and 4 seconds, respectively, the PSL particle removal rates are 12.2% and 14. Since it is 6%, when the thinner on the surface of the inspection wafer W is removed, the rotation speed of the inspection wafer W is set to 3000 rpm and N ₂ gas is supplied toward the inspection wafer W. Thus, it can be said that particles can be efficiently removed even in a short time. Further, as shown in FIG. 17, since the removal rate of PSL particles is high in both verification test 3-4a and verification test 3-4b, when the wafer W is dried, N ₂ gas should be blown to dry it. Therefore, it can be said that the particles can be efficiently removed even when the time for supplying the thinner is subsequently set to be short.

[Verification test 4]
Further, in intermittently supplying the thinner to the inspection wafer W, the drying time when the thinner is stopped and the wafer W is dried, 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. Was verified.
[Verification test 4-1]
In the verification test 3-4b, when the thinner on the surface of the inspection wafer W is removed, the rotation speed of the inspection wafer W is set to 3000 rpm while supplying N ₂ gas toward the inspection wafer W. A verification test 4-1 was made by using an example of rotating for 3 seconds.
[Verification test 4-2]
Further, following the process of the verification test 4-1, while the thinner is stopped, the inspection wafer W is rotated at 1000 rpm for 3 seconds to supply N ₂ gas and remove the thinner on the surface of the inspection wafer W. After that, further, an example in which the thinner was supplied toward the center of the wafer W for 3 seconds while rotating the inspection wafer W at a rotation speed of 1000 rpm was set as verification test 4-2.
Regarding the verification tests 4-1 and 4-2, similarly, the difference value between the number of pre-test adherence of PSL particles and the number of post-test adherence of PSL particles on the inspection wafer W was obtained, and the PSL particle removal rate was calculated.

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

According to this result, the removal rate of particles is increased by prolonging the time for supplying the N ₂ gas while rotating the inspection wafer W with the thinner stopped, and further increasing the inspection wafer W with the thinner stopped. It can be said that the removal rate of particles is increased by repeating the step of supplying N ₂ gas while rotating the wafer and the step of supplying thinner to the surface of the inspection wafer W while rotating the inspection wafer W.

  As described above, when the thinner supply time is increased, when the rotation speed of the wafer W is increased, and when the thinner flow rate is increased, the particle removal rate is increased. Particularly, after the thinner is supplied and dried, the thinner is further supplied. By doing so, it can be said that particles can be removed efficiently. Further, by blowing gas onto the wafer W when the wafer W is dried, the drying time can be shortened and the flow rate of the thinner can be reduced. Further, by repeating the step of supplying thinner to the wafer W and the step of drying the wafer W a plurality of times, particles can be removed more efficiently.

  Further, an SOC film was formed successively on the inspection wafer W which was subjected to the processes of the reference example, the verification test 3-4b and the verification test 4, and the number of comet spots formed on the SOC film was counted. The numbers of comet spots counted on each of the inspection wafers W in the reference example, the verification test 3-4b, and the verification test 4 were 214 pieces, 118 pieces, and 7 pieces, respectively. It can be seen that in the verification test 3-4b, the number of comet spots was greatly reduced compared to the reference example, and in the verification test 4, it was further reduced.

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

2 cup body 3 coating liquid nozzle 4 thinner nozzle 5 N ₂ gas nozzle 6 nozzle unit 100 thinner 101 particles 102 coating liquid W wafer

Claims (13)

Holding the substrate horizontally,
Next, a step of wetting the entire surface of the substrate with the processing liquid,
Then, rotating the substrate around a vertical axis , shaking off the treatment liquid on the surface of the substrate, and drying the surface of the substrate,
And then supplying a cleaning liquid, which is an organic solvent, to the surface of the substrate while rotating the substrate whose surface is dried around a vertical axis,
It is seen containing a step of forming a coating film by supplying a coating solution to the surface of Thereafter the substrate, and
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;
After that, the step of supplying the cleaning liquid to the surface of the substrate while rotating the substrate having the dried surface around a vertical axis is performed .   The coating method according to claim 1, wherein the treatment liquid is either tetramethylammonium hydroxide or an ammonia / hydrogen peroxide / water mixed liquid.   The coating method according to claim 1, wherein the treatment liquid and the cleaning liquid are the same organic solvent. Drying the surface of the substrate by rotating the substrate around a vertical axis, any one of 3 claims 1, characterized in that for discharging a gas toward the substrate rotates the substrate about a vertical axis The coating method according to item . The step of wetting the entire surface of the substrate with the treatment liquid supplies the treatment liquid to the surface of the substrate while rotating the substrate around the vertical axis,
2. The rotating direction of the substrate in the step of wetting the entire surface of the substrate with the processing liquid and the rotating direction of the substrate in the step of supplying the cleaning liquid to the substrate for the first time are opposite directions to each other. 5. The coating method according to any one of 4 to 4 . In the step of supplying the cleaning liquid to the surface of the substrate, the step of supplying the cleaning liquid to the substrate immediately before the step of supplying the coating liquid to the surface of the substrate to form the coating film supplies the cleaning liquid to the surface of the other substrate. 6. The coating method according to claim 1, wherein the cleaning liquid is supplied for a longer period of time than the step of performing. Supply time of the treatment liquid in the step of wetting the processing liquid across the surface of the substrate, any one of claims 1 to 6, characterized in that shorter than the supply time of the cleaning liquid in the step of supplying a cleaning liquid to the surface of the substrate The coating method according to item . 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 peripheral edge of the substrate. The coating method according to any one of claims 1 to 7 . Held horizontally, a storage medium storing a computer program for use in a coating apparatus for coating by supplying the coating liquid to the substrate is rotated about a vertical axis, according to any one of claims 1 to 8 A storage medium in which steps are assembled so as to execute the coating method of. A substrate holding portion for holding the substrate horizontally,
A rotation mechanism for rotating the substrate holding unit around a vertical axis,
A coating liquid nozzle for supplying a coating liquid to the substrate held by the substrate holding part,
A processing liquid nozzle for supplying a processing liquid to the substrate held by the substrate holding part;
A cleaning liquid nozzle that supplies a cleaning liquid that is an organic solvent to the substrate held by the substrate holding unit,
Holding the substrate horizontally, then wetting the entire surface of the substrate with the processing liquid, and then rotating the substrate around a vertical axis to shake off the processing liquid on the surface of the substrate and dry the surface of the substrate. a step of, steps thereafter the step of supplying the cleaning solution to the dried surface of the substrate while rotating the substrate about a vertical axis of the surface, then rotating the substrate around a vertical axis, to dry the surface of the substrate Then , a step of supplying the cleaning liquid to the surface of the substrate while rotating the substrate whose surface has been dried around a vertical axis, and then supplying a coating liquid to the surface of the substrate to form a coating film. And a control unit that executes the following. The coating apparatus according to claim 10 , wherein the processing liquid and the cleaning liquid are the same solvent, and the processing liquid nozzle and the cleaning liquid nozzle are commonly used. Equipped with a gas supply nozzle that supplies gas toward the substrate,
Wherein the control unit, wherein in the step of drying the surface of the substrate, to claim 10 or 11 and outputs a control signal to discharge gas toward the substrate while rotating the substrate about a vertical axis Coating equipment.   The step of wetting the entire surface of the substrate with the treatment liquid supplies the treatment liquid to the surface of the substrate while rotating the substrate around a vertical axis,
  11. The rotation direction of the substrate in the step of wetting the entire surface of the substrate with the treatment liquid and the rotation direction of the substrate in the step of supplying the cleaning liquid to the substrate for the first time are opposite to each other. 13. The coating apparatus according to any one of 1 to 12.

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