Substrate processing apparatus and substrate processing method
After a solvent is discharged onto a substrate in a period from a time point t 0 to a time point t 1 , rotation of the substrate is started at a time point t 2 . A resist liquid is discharged onto a center portion of a target surface of the substrate at a time point t 3 . A rotation speed of the substrate starts to decrease at a time point t 4 , and attains a first speed after a certain period of time. The discharge of the resist liquid is stopped at a time point t 5 . The rotation of the substrate is accelerated in a period from a time point t 6 to a time point t 7 , and the rotation speed of the substrate attains a second speed at the time point t 7 . The rotation of the substrate is decelerated in a period from the time point t 7 to a time point t 8 , and the rotation speed of the substrate attains a third speed at the time point t 8 . Here, deceleration of the rotation of the substrate in the period from the time point t 7 to the time point t 8 is smaller than acceleration of the rotation of the substrate in the period from the time point t 6 to the time point t 7.
1. A substrate processing method for forming a film of a coating liquid on a substrate, comprising the steps of:
rotating the substrate in a horizontal attitude;
supplying the coating liquid onto the substrate that is rotated;
increasing a rotation speed of the substrate from a first speed to a second speed in a first period after supply of said coating liquid; and
decreasing the rotation speed of the substrate from said second speed to a third speed in a second period immediately after said first period, wherein
deceleration of rotation of the substrate in said second period is smaller than acceleration of rotation of the substrate in said first period.
2. The substrate processing method according to claim 1 , wherein said step of increasing the rotation speed of the substrate from the first speed to the second speed in the first period after the supply of said coating liquid includes spreading the coating liquid over a peripheral portion of the substrate while drying the coating liquid on a center portion of the substrate.
3. The substrate processing method according to claim 1 , wherein said step of decreasing the rotation speed of the substrate from said second speed to the third speed in said second period includes making a reduction in a centrifugal force applied to the coating liquid on the center portion of the substrate smaller than a reduction in the centrifugal force applied to the coating liquid on the peripheral portion of the substrate.
4. The substrate processing method according to claim 1 , wherein said step of rotating the substrate in the horizontal attitude includes setting the rotation speed of the substrate when the supply of the coating liquid is started to a fourth speed that is higher than said third speed.
5. The substrate processing method according to claim 4 , wherein said step of supplying the coating liquid onto the substrate that is rotated includes setting the rotation speed of the substrate to said first speed by end of the supply of the coating liquid, wherein
said first speed is lower than said third speed.
6. The substrate processing method according to claim 4 , wherein said step of supplying the coating liquid onto the substrate that is rotated includes:
setting the rotation speed of the substrate to a fifth speed that is lower than said first speed and said third speed by the end of the supply of the coating liquid.
7. The substrate processing method according to claim 4 , wherein said step of supplying the coating liquid onto the substrate that is rotated includes setting the rotation speed of the substrate to said first speed in a period from the start of the supply of the coating liquid to start of said first period, wherein
said first speed is equal to said fourth speed.
8. The substrate processing method according to claim 1 , further comprising the step of performing one or a plurality of cycles in which the rotation speed of the substrate is reduced immediately after the rotation speed of the substrate is increased after said second period, wherein
the deceleration of the rotation of the substrate in each of the cycles is smaller than the acceleration of the rotation of the substrate.
9. The substrate processing method according to claim 1 , wherein the acceleration of the rotation of the substrate in said first period is not less than 10000 rpm/s, and the deceleration of the rotation of the substrate in said second period is smaller than 10000 rpm/s.
10. The substrate processing method according to claim 1 , wherein said second speed is not less than 2000 rpm.